Mic reduction with lithium ions

ABSTRACT

The invention relates to a process for reducing the minimum inhibitory concentration (MIC) of a biocide against at least one strain of bacteria and/or at least one strain of yeast and/or at least one strain of mould in an aqueous preparation. The invention further relates to the use of a water soluble source of lithium ions for reducing the minimum inhibitory concentration (MIC) of a biocide against at least one strain of bacteria and/or at least one strain of yeast and/or at least one strain of mould in an aqueous preparation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. national phase of PCT Application No. PCT/EP2015/057637,filed Apr. 8, 2015, which claims priority to European Application No.14164224.9, filed Apr. 10, 2014.

The invention relates to a process for reducing the minimum inhibitoryconcentration (MIC) of a biocide against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldin an aqueous preparation. The invention further relates to the use of awater soluble source of lithium ions for reducing the minimum inhibitoryconcentration (MIC) of a biocide against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldin an aqueous preparation.

In practice, aqueous preparations and especially suspensions,dispersions or slurries of water-insoluble solids such as minerals,fillers or pigments are used extensively in the paper, paint, rubber andplastics industries as coatings, fillers, extenders and pigments forpapermaking as well as aqueous lacquers and paints. For example,suspensions or slurries of calcium carbonate, talc or kaolin are used inthe paper industry in large amounts as filler and/or as a component inthe preparation of coated paper. Typical aqueous preparations ofwater-insoluble solids are characterized in that they comprise water, awater-insoluble solid compound and optionally further additives, such asdispersing agents, in the form of a suspension, a slurry or dispersionwith a water-insoluble solid content of 0.1 to 99.0 wt.-% based on thetotal weight of the preparation. A typical aqueous preparation is aWhite Mineral Dispersion (WMD) having a solids content of 45.0 to 78.0wt.-%. Water-soluble polymers and copolymers which may be used as e.g.dispersant and/or grinding aid in such preparation are, for example,described in U.S. Pat. No. 5,278,248.

The aforementioned aqueous preparations are often subject tocontamination by microorganisms such as fungi, yeasts, protozoa and/oraerobic and anaerobic bacteria resulting in changes in the preparationproperties such as changes in viscosity and/or pH, discolorations orreductions in other quality parameters, which negatively affect theircommercial value. Therefore, the manufacturers of such aqueouspreparations usually take measures for stabilizing the suspensions,dispersions or slurries. For example, it is known that numerous biocidesmay reduce the growth and accumulation of such microorganisms in aqueouspreparations and, thus, reduce the tendency of undesired alterations ofthese preparations, like viscosity changes or unpleasant odours.

For ensuring an acceptable microbiological quality of aqueouspreparations, preservatives or biocides are used over the entire lifecycle of the preparation (production, storage, transport, use). In theart, several approaches for improving the microbiological quality ofaqueous preparations have been proposed. For example, EP 1 139 741describes aqueous suspensions or dispersions of minerals, fillers and/orpigments, containing a microbiocidal agent in the form of a solution andderivatives of phenol in partially neutralized form. U.S. Pat. No.5,496,398 relates to a process for the reduction of microorganisms inkaolin clay slurries by a combination of low temperature heat andreduced levels of a microbiocidal agent. WO 02/052941 describes biocidecompositions for incorporation into paints, coating, plasters andplastics comprising at least one metal oxide and at least one metalsalt. US 2006/0111410 mentions a mixture comprising1,2-benzisothiazolinone (BIT) and tetramethylolacetylenediurea (TMAD)for protecting industrial materials and products against attack anddestruction by microorganisms. Furthermore, it is suggested in the artto add formaldehyde-releasing substances to such aqueous preparationsfor improving the microbiological quality. For example, U.S. Pat. No.4,655,815 mentions a antimicrobial composition comprising a formaldehydedonor. Furthermore, WO 2006/079911 describes a method of protectionagainst microorganisms by increasing the OH⁻ ion concentration of thesuspension.

WO 2004/040979 A1 relates to synergic antimicrobial mixtures containing1,2-benzisothiazolinon (BIT) and benzylhemiformal (BHF). Thecorresponding mixtures are used, for example, for slurries of pigments.EP 1 661 587 A1 relates to germicidal compositions includingphthalaldehyde as an active ingredient. It is indicated in EP 1 661 587A1 that halide ions, carbonate salts and bicarbonate salts may enhancethe germicidal efficacy of phthalaldehyde against highly resistantBacillus subtilis spores. US 2001/0009682 A1 relates to disinfectantconcentrates having improved biocidal activity which may contain analdehyde such as glutaraldehyde, a glycol and a lithium based buffer. Itis described in US 2001/0009682 A1 that the buffer is required tocontrol the pH of both the concentrate and its dilutions within thedesired biocidal effective range. EP 2 199 348 A1 relates to a processfor manufacturing aqueous mineral material suspensions or dried mineralmaterials using at least one lithium ion neutralised water-solubleorganic polymer as well as the use of the lithium ion neutralisedwater-soluble organic polymer in the manufacturing process as adispersing and/or grinding enhancer. EP 2 374 353 A1 refers to a processfor preserving an aqueous preparation of mineral material like e.g.calcium carbonate preparations. EP 2 596 702 A1 refers to a process forstabilising an aqueous mineral preparation comprising a step of addingat least one aldehyde-containing and/or aldehyde-releasing and/orphenolic and/or isothiazoline biocide to said aqueous mineralpreparation. U.S. Pat. No. 4,871,754 refers to aqueous solutions whichare protected from infestation by micro-organisms by use of a biocidewhich is an aqueous formulation of the lithium salt of1,2-benzisothiazolin-3-one. EP 2 272 348 A1 refers to a biocidal agent(I) comprising 98% of one or more halogen-free isothiazolinones, and1-500 wt.ppm of copper(II)-ions. It is further described that BIT may beprovided in the form of its alkali metal salt. However, none of saiddocuments is concerned with a process for reducing the minimuminhibitory concentration (MIC) of a biocide against at least one strainof bacteria and/or at least one strain of yeast and/or at least onestrain of mould in an aqueous preparation by the addition of at leastone water soluble source of lithium ions.

Furthermore, the applicant is aware of EP 2 108 260 A2 referring to aprocess for bacterial stabilising aqueous preparations like e.g. calciumcarbonate slurries and a composition which can be used for the biocidaltreatment of such aqueous preparations. In particular, EP 2 108 260 A2describes that said preparation comprises at least one mineral and atleast one strain of bacteria which is resistant to, tolerant to and/ordegrade aldehyde-releasing and/or aldehyde-based biocides. Thus, thebiocide alone shows no effect against the bacteria present in thepreparation such that an unhindered growth of bacteria is observed.Furthermore, due to the bacteria which are considered as being resistantto, tolerant to and/or degrade the aldehyde-releasing or aldehyde-basedbiocide present in the preparation, no minimum inhibitory concentration(MIC) of the biocide was determined.

The use of biocides in aqueous preparations is subject to continuouslyincreasing limitations especially regarding the biocide concentrations.

However, at reduced biocide concentration the efficacy of the respectivebiocide against bacteria, yeasts and/or moulds is usually notsatisfactory anymore in comparison to the biocidal efficacy observed ata higher concentration of the same biocide and, thus, the obtainedbiocidal action at reduced biocide concentration is typicallyinsufficient to avoid microbially induced alteration of aqueouspreparations.

Therefore, there is still a need in the art for adequate processes forproviding sufficient biocidal activity in aqueous preparations such assolutions, suspensions, dispersions and slurries in order to achieve alonger lasting and sufficient stabilization of the aqueous preparationsat reduced biocide concentration. In other words, there is still a needfor processes for providing sufficient biocidal activity in aqueouspreparations in which the effective biocide concentration is below theminimum inhibitory concentration (MIC) of the respective biocide.

Thus, it is an objective of the present invention to provide a processfor providing sufficient biocidal activity in aqueous preparations suchas solutions, suspensions, dispersions and slurries at reduced biocideconcentration. In particular, it is thus an objective of the presentinvention to provide a process for reducing the minimum inhibitoryconcentration (MIC) of a biocide against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldin the aqueous preparation. A further objective of the present inventionis to provide a process for reducing the minimum inhibitoryconcentration (MIC) of a biocide such that the growth and accumulationof microorganisms in aqueous preparations are reduced or prevented and,thus, significantly reducing the tendency of alterations of thesepreparations and maintaining their desired chemical and mechanicalproperties such as viscosity, pH, brilliance and colour and preventingbad odour. Another objective of the present invention is to provide aprocess for reducing the minimum inhibitory concentration (MIC) of abiocide which is effective against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldin the aqueous preparation. Another objective is to provide a processfor reducing the minimum inhibitory concentration (MIC) of a biocidesuch that a bacterial stabilisation and/or disinfection and/orpreservation and/or control of the microbial contamination of aqueouspreparations is given. Even a further objective of the invention is toprovide an aqueous composition which provides sufficient biocidalactivity in aqueous preparations at reduced biocide concentration, i.e.at a biocide concentration which is below the minimum inhibitoryconcentration (MIC) of the respective biocide in the absence of acompound reducing the minimum inhibitory concentration (MIC reducingcompound).

These and other objectives of the present invention can be solved by aprocess and an aqueous preparation as described in the present inventionand defined in the claims.

According to one aspect of the present application a process forreducing the minimum inhibitory concentration (MIC) of a biocide againstat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould in an aqueous preparation isprovided. The process comprises the steps of:

-   -   a) providing an aqueous preparation,    -   b) providing at least one biocide,    -   c) providing at least one water soluble source of lithium ions,    -   d) contacting the aqueous preparation of step a) with the at        least one biocide of step b), wherein the at least one biocide        is effective against at least one strain of bacteria and/or at        least one strain of yeast and/or at least one strain of mould        when present in the aqueous preparation,    -   e) contacting the aqueous preparation of step a) before and/or        during and/or after step d) with the at least one water soluble        source of lithium ions of step c) in an amount such that the        minimum inhibitory concentration (MIC) of the at least one        biocide against the at least one strain of bacteria and/or at        least one strain of yeast and/or at least one strain of mould        fulfils the equation (I)        MIC_(withoutLi)/MIC_(Li)≥1.1  (I)        -   wherein        -   MIC_(withoutLi) is the minimum inhibitory concentration            (MIC) of the at least one biocide against the at least one            strain of bacteria and/or at least one strain of yeast            and/or at least one strain of mould without the at least one            water soluble source of lithium ions in ppm, calculated            relative to the weight of water in the aqueous preparation            of step a),        -   MIC_(Li) is the minimum inhibitory concentration (MIC) of            the at least one biocide against the at least one strain of            bacteria and/or at least one strain of yeast and/or at least            one strain of mould with the at least one water soluble            source of lithium ions in ppm, calculated relative to the            weight of water in the aqueous preparation of step a),            wherein the at least one water soluble source of lithium            ions is present in the water phase of the aqueous            preparation such that the total amount of lithium ions is            from 15.0 to 800.0 mMol/L, calculated relative to the weight            of water in the aqueous preparation, and wherein the at            least one biocide is present in the water phase of the            aqueous preparation in an amount of from 0.4 to 6 500.0 ppm,            calculated relative to the weight of water in the aqueous            preparation.

In accordance with the present invention, the lithium ions of the atleast one water soluble source of lithium ions may be regarded as acompound reducing the minimum inhibitory concentration (MIC reducingcompound) of a biocide. When subsequently reference is made to a MICreducing compound, the lithium ions of the at least one water solublesource of lithium ions is meant.

The term “minimum inhibitory concentration (MIC)” refers to the lowestconcentration of the respective biocide required for preventing orreducing the growth and/or accumulation of the at least one strain ofbacteria and/or at least one strain of yeast and/or at least one strainof mould in the aqueous preparation, i.e. when the bacterialconcentration dropped below 100 cfu/plate measured in accordance withthe method for determining the MIC as described in the example section.

In the meaning of the present invention, a “MIC reducing compound” is acompound which induces or effects a biocidal activity (e.g. reduction orprevention of the growth and/or accumulation of microorganisms such asbacteria, yeasts and/or moulds) in an aqueous preparation containing abiocide concentration which is below the minimum inhibitoryconcentration (MIC) of the respective biocide in the absence of the MICreducing compound (other than a content of dissolved lithium ions whichmay naturally be present in the aqueous preparation).

Accordingly, the wording “process for reducing the minimum inhibitoryconcentration (MIC) of a biocide against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldin an aqueous preparation” means that a biocidal activity of a biocideis induced or effected by the at least one water soluble source oflithium ions leading to a MIC which is below the MIC of the biocide inthe absence of the at least one water soluble source of lithium ions.

In the meaning of the present invention, biocides which are “effective”against at least one strain of bacteria and/or at least one strain ofyeast and/or at least one strain of mould refer to biocides having theability to prevent or reduce the growth or accumulation of the at leastone strain of bacteria and/or at least one strain of yeast and/or atleast one strain of mould in the aqueous preparation when dosed in usualamounts (e.g. as proposed by the supplier of the biocide).

According to the present invention, the wording “prevent or reduce thegrowth or accumulation” means that no significant growth or accumulationof the at least one strain of bacteria and/or at least one strain ofyeast and/or at least one strain of mould is observed in the aqueouspreparation when the biocide is present. This preferably leads to areduction of the cfu value (colony forming unit) in the treated aqueouspreparation compared to the preparation immediately before treatment,more preferably to a value of less than 100 cfu/plate and even morepreferably to a value of less than 80 cfu/plate using the bacterialcount method described in the example section herein.

According to the present invention, a “significant growth oraccumulation” of the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould is observed if thedifference, i.e. the growth of the of the at least one strain ofbacteria and/or at least one strain of yeast and/or at least one strainof mould is greater than the error associated with the measurementtechnique when tested within one-week and measured by plate-out on atryptic soy agar (TSA), where the plates are incubated at 30° C. andevaluated after 48 hours, according to the bacterial count methoddescribed in the Example section herein.

According to the present invention, the lithium ion content in theaqueous preparation can be evaluated by filtering off the solids in thesuspension by membrane filtration (pore size of 0.2 microns) andmeasuring the lithium ion content in the filtrate by ion chromatography.

According to the present invention, the content of the at least onebiocide in the aqueous phase can be evaluated by HPLC (high pressureliquid chromatography). If necessary, the corresponding biocide may beconverted into a derivative before evaluating with HPLC.

Where the term “comprising” is used in the present description andclaims, it does not exclude other elements. For the purposes of thepresent invention, the term “consisting of” is considered to be apreferred embodiment of the term “comprising of”. If hereinafter a groupis defined to comprise at least a certain number of embodiments, this isalso to be understood to disclose a group, which preferably consistsonly of these embodiments.

Where an indefinite or definite article is used when referring to asingular noun, e.g. “a”, “an” or “the”, this includes a plural of thatnoun unless something else is specifically stated.

Terms like “obtainable” or “definable” and “obtained” or “defined” areused interchangeably. This e.g. means that, unless the context clearlydictates otherwise, the term “obtained” does not mean to indicate that,e.g. an embodiment must be obtained by e.g. the sequence of stepsfollowing the term “obtained” even though such a limited understandingis always included by the terms “obtained” or “defined” as a preferredembodiment.

Furthermore, the present invention refers to the use of a water solublesource of lithium ions for reducing the minimum inhibitory concentration(MIC) of a biocide against at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould in anaqueous preparation, wherein the reduction is achieved when the minimuminhibitory concentration (MIC) of the at least one biocide against theat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould fulfils the equation (I), preferablythe equation (Ia), more preferably equation (Ib) and most preferablyequation (Ic)MIC_(withoutLi)/MIC_(Li)≥1.1  (I)MIC_(withoutLi)/MIC_(Li)≥1.5  (Ia)MIC_(withoutLi)/MIC_(Li)≥2.0  (Ib)MIC_(withoutLi)/MIC_(Li)≥4.0  (Ic)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

According to another aspect of the present invention, an aqueouspreparation is provided, wherein the aqueous preparation comprises

-   -   a) from 15.0 to 800.0 mMol/L, calculated relative to the weight        of water in the aqueous preparation, of lithium ions in the        water phase of the aqueous preparation, and    -   b) at least one biocide being effective against at least one        strain of bacteria and/or at least one strain of yeast and/or at        least one strain of mould,        wherein the aqueous preparation comprises the at least one        biocide in an amount such that the minimum inhibitory        concentration (MIC) of the at least one biocide against the at        least one strain of bacteria and/or at least one strain of yeast        and/or at least one strain of mould fulfils the equation (I)        MIC_(withoutLi)/MIC_(Li)/MIC_(Li)≥1.1  (I)        where        MIC_(withoutLi) is the minimum inhibitory concentration (MIC) of        the at least one biocide against the at least one strain of        bacteria and/or at least one strain of yeast and/or at least one        strain of mould without the water soluble lithium ions in ppm,        calculated relative to the weight of water in the aqueous        preparation.        MIC_(Li) is the minimum inhibitory concentration (MIC) of the at        least one biocide against the at least one strain of bacteria        and/or at least one strain of yeast and/or at least one strain        of mould with the water soluble lithium ions in ppm, calculated        relative to the weight of water in the aqueous preparation.

When in the following reference is made to preferred embodiments ortechnical details of the inventive process for reducing the minimuminhibitory concentration (MIC) of a biocide against at least one strainof bacteria and/or at least one strain of yeast and/or at least onestrain of mould in an aqueous preparation, it is to be understood thatthese preferred embodiments or technical details also refer to theinventive aqueous preparation and the inventive use of the water solublesource of lithium ions as defined herein (as far as applicable). If, forexample, it is set out that the aqueous preparation of the inventiveprocess preferably comprises at least one inorganic particulatematerial, also the inventive aqueous preparation as well as the usepreferably comprises at least one inorganic particulate material.

According to one embodiment of the present invention, the aqueouspreparation of step a) comprises (i) at least one inorganic particulatematerial, preferably the at least one inorganic particulate material isselected from the group comprising natural ground calcium carbonate,natural and/or synthetic precipitated calcium carbonate, dolomite,kaolin, talcum, aluminium hydroxide, aluminium silicate, titaniumdioxide and mixtures thereof, and most preferably the at least oneinorganic particulate material comprises natural ground calciumcarbonate and/or synthetic precipitated calcium carbonate, and/or (ii)at least one organic material, preferably the at least one organicmaterial is selected from the group comprising carbohydrates such asstarch, sugar, cellulose and cellulose based pulp, glycerol,hydrocarbons and mixtures thereof.

According to another embodiment of the present invention, the aqueouspreparation of step a) and/or of step d) and/or of step e) has (i) pHvalue of from 2 to 12, preferably from 6 to 12 and more preferably from7 to 10.5, and/or (ii) solids content of up to 85.0 wt.-%, preferablyfrom 10.0 to 82.0 wt.-%, and more preferably from 20.0 to 80.0 wt.-%,based on the total weight of the aqueous preparation.

According to yet another embodiment of the present invention, the atleast one strain of bacteria is selected from the group consisting ofgram-negative bacteria, gram-positive bacteria and mixtures thereof.

According to one embodiment of the present invention, (i) the at leastone strain of bacteria is selected from the group comprising,Methylobacterium sp., Salmonella sp., Escherichia sp. such asEscherichia coli, Shigella sp., Enterobacter sp., Pseudomonas sp. suchas Pseudomonas mendocina, Bdellovibrio sp., Agrobacterium sp.,Alcaligenes sp., Flavobacterium sp., Rhizobium sp., Sphingobacteriumsp., Aeromonas sp., Chromobacterium sp., Vibrio sp., Hyphomicrobium sp.,Leptothrix sp., Micrococcus sp., Staphylococcus sp. such asStaphylococcus aureus, Agromyces sp., Acidovorax sp., and mixturesthereof, and/or (ii) the at least one strain of yeast is selected fromthe group comprising Saccharomycotina, Taphrinomycotina,Schizosaccharomycetes, Basidiomycota, Agaricomycotina, Tremellomycetes,Pucciniomycotina, Microbotryomycetes, Candida sp. such as Candidaalbicans, Candida tropicalis, Candida stellatoidea, Candida glabrata,Candida krusei, Candida guilliermondii, Candida viswanathii, Candidalusitaniae and mixtures thereof, Yarrowia sp. such as Yarrowialipolytica, Cryptococcus sp. such as Cryptococcus gattii and Cyptococcusneofarmans, Zygosaccharomyces sp., Rhodotorula sp. such as Rhodotorulamucilaginosa, and mixtures thereof, and/or (iii) the at least one strainof mould is selected from the group comprising of Acremonium sp.,Alternaria sp., Aspergillus sp., Cladosporium sp., Fusarium sp., Mucorsp., Penicillium sp., Rhizopus sp., Stachybotrys sp., Trichoderma sp.,Dematiaceae sp., Phoma sp., Eurotium sp., Scopulariopsis sp.,Aureobasidium sp., Monilia sp., Botrytis sp., Stemphylium sp.,Chaetomium sp., Mycelia sp., Neurospora sp., Ulocladium sp.,Paecilomyces sp., Wallemia sp., Curvularia sp., and mixtures thereof.

According to another embodiment of the present invention, the at leastone biocide of step b) is selected from the group comprising phenols,halogenated phenols, halogen-containing compounds, halogen-releasingcompounds, isothiazolinones, aldehyde-containing compounds,aldehyde-releasing compounds, guanidines, sulphones, thiocyanates,pyrithiones, antibiotics such as β-lactam antibiotics, quaternaryammonium salts, peroxides, perchlorates, amides, amines, heavy metals,biocidal enzymes, biocidal polypeptides, azoles, carbamates,glyphosates, sulphonamides and mixtures thereof.

According to yet another embodiment of the present invention, the atleast one water soluble source of lithium ions is at least one lithiumsalt, preferably the at least one lithium salt is selected from lithiumcarbonate, lithium chloride, lithium hydroxide, lithium phosphate,lithium citrate, lithium maleate, lithium acetate and lithium lactate,polymeric salts of lithium and mixtures thereof, said polymeric salt oflithium is preferably selected from lithium salts of acrylichomopolymers, acrylic copolymers such as copolymers of acrylic acid andmaleic acid and/or acrylamide, polyphosphates and mixtures thereof, saidpolymeric salt of lithium is more preferably Li₂Na₂polyphosphate,lithium-sodium hexamethaphosphate or lithium polyacrylate.

According to one embodiment of the present invention, step d) is carriedout in that the at least one biocide is added to the aqueous preparation(i) in an amount being at least 9%, preferably at least 33%, morepreferably at least 50% and most preferably at least 75%, below theminimum inhibitory concentration (MIC) of the at least one biocide forthe at least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould, and/or (ii) in an amount of from0.5 ppm to 6 000 ppm, calculated relative to the weight of water in theaqueous preparation.

According to another embodiment of the present invention, step e) iscarried out such that the minimum inhibitory concentration (MIC) of theat least one biocide against the at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould fulfilsthe equation (Ia), preferably equation (Ib) and most preferably equation(Ic)MIC_(withoutLi)/MIC_(Li)≥1.5  (Ia)MIC_(withoutLi)/MIC_(Li)≥2.0  (Ib)MIC_(withoutLi)/MIC_(Li)≥4.0  (Ic)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of thebiocide against the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould without the at leastone water soluble source of lithium ions in ppm calculated relative tothe weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the biocideagainst the at least one strain of bacteria and/or at least one strainof yeast and/or at least one strain of mould with the at least one watersoluble source of lithium ions in ppm calculated relative to the weightof water in the aqueous preparation of step a).

According to yet another embodiment of the present invention, step e) iscarried out in that the at least one water soluble source of lithiumions is added to the aqueous preparation in an amount such that thetotal amount of lithium ions in the water phase of the aqueouspreparation is from 15.0 to 700.0 mMol/L, calculated relative to theweight of water in the preparation.

According to one embodiment of the present invention, step e) is carriedout before step d).

According to another embodiment of the present invention, step d) and/orstep e) is/are repeated one or more times.

According to yet another embodiment of the present invention, theaqueous preparation of step d) and/or e) is/are free ofaldehyde-releasing and/or aldehyde-based biocides in an amount of 250.0to 5 000.0 ppm, calculated relative to the weight of water in thepreparation, when strains of bacteria which are resistant to, tolerantto and/or degrade aldehyde-releasing and/or aldehyde-based biocides arepresent in the aqueous preparation.

As set out above, the inventive process for reducing the minimuminhibitory concentration (MIC) of a biocide against at least one strainof bacteria and/or at least one strain of yeast and/or at least onestrain of mould in an aqueous preparation comprises the steps a), b),c), d) and e). In the following, it is referred to further details ofthe present invention and especially the foregoing steps of theinventive process for reducing the minimum inhibitory concentration(MIC) of a biocide against at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould in anaqueous preparation. Those skilled in the art will understand that manyembodiments described herein can be combined or applied together.

Characterisation of Step a): Provision of an Aqueous Preparation

According to step a) of the process of the present invention, an aqueouspreparation is provided.

It is appreciated that the aqueous preparation provided in step a) ofthe instant process can be any aqueous preparation that requiresbiocidal activity, i.e. reduction or prevention of the growth and/oraccumulation of at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould.

The term “aqueous” preparation refers to a system, wherein the liquidphase of the preparation comprises, preferably consists of, water.However, said term does not exclude that the aqueous preparationcomprises an organic solvent selected from the group comprising alcoholssuch as methanol, ethanol, isopropanol, carbonyl-group containingsolvents such as ketones, e.g. acetone or aldehydes, esters such asisopropyl acetate, carboxylic acids such as formic acid, sulphoxidessuch as dimethyl sulphoxide and mixtures thereof. If the aqueouspreparation comprises an organic solvent, the aqueous preparationcomprises the organic solvent in an amount up to 40.0 wt.-% preferablyfrom 1.0 to 30.0 wt.-% and most preferably from 1.0 to 25.0 wt.-%, basedon the total weight of the liquid phase of the aqueous preparation. Forexample, the liquid phase of the aqueous preparation consists of water.If the liquid phase of the aqueous preparation consists of water, thewater to be used can be any water available such as tap water and/ordeionised water.

The aqueous preparation of step a) can be an aqueous solution or anaqueous suspension. In one embodiment of the present invention, theaqueous preparation of step a) is an aqueous suspension.

The term “aqueous solution” in the meaning of the present inventionrefers to systems in which no discrete solid particles are observed inthe solvent, i.e. in case a further material, such as at least oneorganic material, are present, a solution with water is formed, whereinthe possible particles of the further material are dissolved in thesolvent.

The term “aqueous suspension” in the meaning of the present inventionrefers to a system comprising solvent and at least one inorganicparticulate material and/or at least one organic material, wherein atleast a part of the particles of the at least one inorganic particulatematerial and/or the at least one organic material are present asinsoluble solids in the solvent.

The aqueous preparation provided in step a) preferably comprises atleast one inorganic particulate material.

The term “at least one” inorganic particulate material in the meaning ofthe present invention means that the inorganic particulate materialcomprises, preferably consists of, one or more inorganic particulatematerials.

In one embodiment of the present invention, the at least one inorganicparticulate material comprises, preferably consists of, one inorganicparticulate material. Alternatively, the at least one inorganicparticulate material comprises, preferably consists of, two or moreinorganic particulate materials. For example, the at least one inorganicparticulate material comprises, preferably consists of, two or threeinorganic particulate material. Preferably, the at least one inorganicparticulate material comprises, preferably consists of, one inorganicparticulate material.

For example, the at least one inorganic particulate material is selectedfrom the group comprising natural ground calcium carbonate, naturaland/or synthetic precipitated calcium carbonate, dolomite, kaolin,talcum, aluminium hydroxide, aluminium silicate, titanium dioxide andmixtures thereof.

In one embodiment of the present invention, the at least one inorganicparticulate material comprises natural ground calcium carbonate and/orsynthetic precipitated calcium carbonate.

“Ground calcium carbonate” (GCC) in the meaning of the present inventionis a calcium carbonate obtained from natural sources, such as limestone,marble or chalk, and processed through a treatment such as grinding,screening and/or fractionizing by wet and/or dry, for example by acyclone or classifier.

“Precipitated calcium carbonate” (PCC) in the meaning of the presentinvention is a synthesized material, generally obtained by precipitationfollowing reaction of carbon dioxide and lime in an aqueous environmentor by precipitation of a calcium and carbonate ion source in water.

The natural ground calcium carbonate and/or synthetic precipitatedcalcium carbonate may additionally be surface treated, for example withfatty acids such as stearic acid and corresponding calcium salts.

If the aqueous preparation provided in step a) comprises at least oneinorganic particulate material, the at least one inorganic particulatematerial may have a particle size distribution as conventionallyemployed for the material(s) involved in the type of product to beproduced. In general, 90% of the particles will have an esd (equivalentspherical diameter as measured by the well known technique ofsedimentation using Sedigraph 5100 series, Micromeritics) of less than 5micrometres (μm). Coarse inorganic particulate materials may have aparticle esd generally (i.e., at least 90 wt.-%) in the range of 1 to 5microns. Fine inorganic particulate materials may have a particle esdgenerally less than 2 μm, e.g. 50.0 to 99.0 wt.-% less than 2 μm andpreferably 60.0 to 90.0 wt.-% less than 2 μm. It is preferred that theat least one inorganic particulate material in the aqueous preparationhas a weight median particle size d₅₀ value of from 0.1 to 5 μm,preferably from 0.2 to 2 μm and most preferably from 0.35 to 1 μm, forexample 0.7 μm as measured using a Sedigraph™ 5100 of MicromeriticsInstrument Corporation.

For keeping such inorganic particulate materials dispersed in an aqueouspreparation and thus ensuring that the viscosity of the preparationremains substantially the same over time, additives such as dispersingagents can be used. A suitable dispersing agent according to the presentinvention is preferably a homo- or copolymer made of monomers and/orco-monomers selected from the group consisting of acrylic acid,methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleicanhydride acid, isocrotonic acid, aconitic acid (cis or trans),mesaconic acid, sinapinic acid, undecylenic acid, angelic acid, canellicacid, hydroxyacrylic acid, acrolein, acrylamide, acrylonitrile,dimethylaminoethyl methacrylate, vinylpyrrolidone, styrene, the estersof acrylic and methacrylic acids and mixtures thereof, wherein salts ofpoly(acrylic acid) and/or poly (methacrylic acid) are preferred asdispersing agent.

Additionally or alternatively, the aqueous preparation of step a)comprises at least one organic particulate material. For example, the atleast one organic material is selected from the group comprising,glycols, carbohydrates such as CMC or starch, cellulose and cellulosebased pulp, glycerol and mixtures thereof.

In one embodiment of the present invention, the aqueous preparation ofstep a) comprises at least one inorganic particulate material,preferably being selected from the group comprising natural groundcalcium carbonate, natural and/or synthetic precipitated calciumcarbonate, dolomite, kaolin, talcum, aluminium hydroxide, aluminiumsilicate, titanium dioxide and mixtures thereof, and most comprisingnatural ground calcium carbonate and/or synthetic precipitated calciumcarbonate

Thus, the aqueous preparation of step a) is preferably an aqueoussuspension.

It is appreciated that the solids content of the aqueous preparationprovided in step a) can be up to 85.0 wt.-%. For example, the solidscontent of the aqueous preparation is from 10.0 to 82.0 wt.-%, and morepreferably from 20.0 to 80.0 wt.-%, based on the total weight of theaqueous preparation.

The total solids content in the meaning of the present applicationcorresponds to the residual weight of the aqueous preparation afterdrying for 3 hours at 105° C. as measured in a sample of at least 3 g to5 g.

The pH of the aqueous preparation provided in step a) can vary in abroad range and is preferably in a pH range typically observed for suchaqueous preparations. It is thus appreciated that the aqueouspreparation of step a) preferably has a pH value of from 2 to 12. Forexample, the aqueous preparation of step a) has a pH value of from 6 to12 and more preferably from 7 to 10.5.

Typically, the aqueous preparations provided in step a) has a viscositybeing preferably in the range from 50 to 2 000 mPa·s and preferably from80 to 800 mPa·s, as measured with a Brookfield DV-II Viscometer at aspeed of 100 rpm and equipped with a LV-3 spindle.

The aqueous preparations according to the invention can be produced bymethods known in the art, by for example, dispersing, suspending orslurring water-insoluble solids, preferably inorganic particulatematerials with, if appropriate, addition of a dispersing agent and, ifappropriate, further additives in water.

Characterisation of Step b): Providing at Least One Biocide

According to step b) of the process of the present invention, at leastone biocide is provided.

The term “at least one” biocide in the meaning of the present inventionmeans that the biocide comprises, preferably consists of, one or morebiocides.

In one embodiment of the present invention, the at least one biocidecomprises, preferably consists of, one biocide. Alternatively, the atleast one biocide comprises, preferably consists of, two or morebiocides. For example, the at least one biocide comprises, preferablyconsists of, two or three biocides. Preferably, the at least one biocidecomprises, preferably consists of, two or more biocides.

The biocide suitable for the present invention may be any biocide beingeffective against at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould in the aqueouspreparation at the minimum inhibitory concentration of the biocide inthe absence of the MIC reducing compound, i.e. the at least one watersoluble source of lithium ions.

Preferred biocides according to the present invention include biocidesbeing selected from the group comprising phenols, halogenated phenols,halogen-containing compounds, halogen-releasing compounds,isothiazolinones, aldehyde-containing compounds, aldehyde-releasingcompounds, guanidines, sulphones, thiocyanates, pyrithiones, antibioticssuch as β-lactam antibiotics, quaternary ammonium salts, peroxides,perchlorates, amides, amines, heavy metals, biocidal enzymes, biocidalpolypeptides, azoles, carbamates, glyphosates, sulphonamides andmixtures thereof.

The phenol biocide of the present invention is preferably 2-phenylphenol(OPP) (CAS NO 90-43-7) and/or 2-phenylphenol (OPP) in the form of thealkali metal salt such as the sodium salt (CAS NO 132-27-4) or potassiumsalt (CAS NO 13707-65-8).

For example, the dosage recommendation by commercial suppliers of suchphenol biocides in the absence of a MIC reducing compound is typicallyfrom 1 500 to 6 000 ppm (w/w) active biocide per aqueous preparationhaving a 75 wt.-% solids content of calcium carbonate.

The halogenated phenol biocide of the present invention is preferably4-chloro-3-methylphenol (CAS NO 59-50-7) and/or 4-chloro-2-methylphenol(CAS NO 1570-64-5).

For example, the dosage recommendation by commercial suppliers of such ahalogenated phenol biocide in the absence of a MIC reducing compound istypically from 3 900 to 25 000 ppm (w/w) active biocide per aqueouspreparation having a 75 wt.-% solids content of calcium carbonate.

The biocide being a halogen-containing or halogen-releasing compound ispreferably selected from bronopol (CAS NO 52-51-7), bronidox (CAS NO30007-47-7), 2,2-dibrom-3-nitrilpropionamid (DBNPA) (CAS NO 10222-01-2),1,2-dibromo-2,4-dicyanobutane (CAS NO 35691-65-7), monochloroamine (CASNO 10599-90-3), ammonium bromide (CAS NO 12124-97-9), calciumhypochlorite (CAS NO 7778-54-3), iodine (CAS NO 7553-56-2), tri-iodide(CAS NO 14900-04-0), potassium iodate (CAS NO 7758-05-6) and mixturesthereof.

In accordance with the present invention, a “halogen-containing biocide”refers to a biocide which has one or more halogen-groups. In accordancewith the present invention, a “halogen-releasing biocide” refers to acompound which is able to release or transfer a halogen group.

For example, the dosage recommendation by commercial suppliers of such ahalogen-containing or halogen-releasing compound (e.g. bronopol) in theabsence of a MIC reducing compound is typically from 300 to 1 500 ppm(w/w) active biocide per aqueous preparation having a 75 wt.-% solidscontent of calcium carbonate.

The isothiazolinone biocide is preferably selected from the groupcomprising isothiazolinone (IT) (CAS NO 1003-07-2), benzisothiazolinone(BIT) (CAS NO 2634-33-5), 5-chloro-2-methyl-2H-isothiazolin-3-one (CMIT)(CAS NO 26172-55-4), 2-methyl-2H-isothiazolin-3-one (MIT) (CAS NO2682-20-4), octylisothiazolinone (OIT) (CAS NO 26530-20-1),dichlorooctylisothiazolinone (DOIT) (CAS NO 64359-81-5) and mixturesthereof. For example, the isothiazolinone biocide CMIT/MIT (CAS NO55965-84-9) is a mixture of 5-chloro-2-methyl-2H-isothiazolin-3-one(CMIT) and 2-methyl-2H-isothiazolin-3-one (MIT) at a weight ratio of3:1.

For example, the dosage recommendation by commercial suppliers of suchan isothiazolinone biocide in the absence of a MIC reducing compound istypically from 25 to 1 500 ppm (w/w) active biocide per aqueouspreparation having a 75 wt.-% solids content of calcium carbonate. Forexample, the dosage recommendation by commercial suppliers ofbenzisothiazolinone (BIT) in the absence of a MIC reducing compound istypically from 240 to 1 500 ppm (w/w) active biocide per aqueouspreparation having a 75 wt.-% solids content of calcium carbonate. Forexample, the dosage recommendation by commercial suppliers of2-methyl-2H-isothiazolin-3-one (MIT) in the absence of a MIC reducingcompound is typically from 75 to 450 ppm (w/w) active biocide peraqueous preparation having a 75 wt.-% solids content of calciumcarbonate. If a mixture of 5-chloro-2-methyl-2H-isothiazolin-3-one(CMIT) and 2-methyl-2H-isothiazolin-3-one (MIT) (weight ratio of 3:1) isused as biocide, the dosage recommendation by commercial suppliers ofsaid mixture in the absence of a MIC reducing compound is typically from27 to 99 ppm (w/w) active biocide per aqueous preparation having a 75wt.-% solids content of calcium carbonate.

The aldehyde-containing compound is preferably selected from the groupcomprising formaldehyde (CAS NO 50-00-0), acetaldehyde, glyoxal,glutaraldehyde (CAS NO 111-30-8), 2-propenal, phthalic dialdehyde andmixtures thereof, and preferably is formaldehyde, glutaraldehyde ormixtures thereof.

In accordance with the present invention, an “aldehyde-containingbiocide” refers to a biocide which has one or more aldehyde-group.

For example, the dosage recommendation by commercial suppliers of suchan aldehyde-containing compound in the absence of a MIC reducingcompound is typically from 300 to 3 000 ppm (w/w) active biocide peraqueous preparation having a 75 wt.-% solids content of calciumcarbonate. For example, the dosage recommendation by commercialsuppliers of Glutaraldehyde in the absence of a MIC reducing compound istypically from 300 to 3000 ppm (w/w) active biocide per aqueouspreparation having a 75 wt.-% solids content of calcium carbonate.

The aldehyde-releasing biocide is preferably selected from the groupcomprising formaldehyde-releasing biocides, acetaldehyde-releasingbiocides, succinaldehyde-releasing biocides, 2-propenal-releasingbiocides and mixtures thereof, preferably from formaldehyde-releasingbiocides. The formaldehyde-releasing biocide is preferably selected fromthe group comprising benzyl alcoholmono(poly)-hemiformal (CAS NO14548-60-8), tetramethylolacetylenediurea (CAS NO 5395-50-6),thiadiazinethione-tetrahydrodimethyl (DAZOMET) (CAS NO 533-74-4),(ethylenedioxy)dimethanol (EDDM) (CAS NO 3586-55-8),2-chloro-N-(hydroxymethyl)acetamide (CAS NO 2832-19-1),dimethyloxazolidine (DMO) (CAS NO 51200-87-4), hexamethylenetetramine(CAS NO 100-97-0), bis[tetrakis(hydroxymethyl)phosphonium] sulphate(THPS) (CAS NO 55566-30-8),1-(cis-3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride (CAS NO51229-78-8), hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine (CAS NO4719-04-4) and mixtures thereof.

In accordance with the present invention, an “aldehyde-releasingbiocide” refers to a compound which is able to release mono- di-, and/ortri-aldehyde.

For example, the dosage recommendation by commercial suppliers of suchan aldehyde-releasing compound in the absence of a MIC reducing compoundis typically from 375 to 750 ppm (w/w) active biocide, e.g. for DAZOMETper aqueous preparation having a 75 wt.-% solids content of calciumcarbonate.

The guanidine biocide is preferably selected from guanidinedodecylmonochloride (CAS NO 13590-97-1) and/or polyethoxyethoxyethylguanidiniumhexachloride (CAS NO 374572-91-5). The sulphone biocide is preferablyhexachlorodimethyl sulfone (CAS NO 3064-70-8) and/or4,4′-Diaminodiphenylsulfone (CAS NO 80-08-0). The thiocyanate biocide ispreferably methylene bis(thiocyanate) (CAS NO 6317-18-6) and/or(Benzothiazol-2-ylthio)methylthiocyanate (CAS NO 21564-17-0). Thebiocide being an antibiotic is preferably selected from β-lactamantibiotics such as penicillin G (CAS NO 69-57-8) and/or ampicillin (CASNO 69-53-4) and/or biapenem (CAS NO 120410-24-4) and/or cefixime (CAS NO79350-37-1). The amide biocide is preferably2,2-dibromo-3-nitrilopropionamide (DBNPA) (CAS NO 10222-01-2). The azolebiocide can be preferably selected from climbazole (CAS NO 38083-17-9),miconazole (CAS NO 22916-47-8), clotrimazole (CAS NO 23593-75-1), andmixtures thereof including the biocides in the form of a salt such asmiconazole nitrate (CAS NO 22832-87-7). The carbamate biocide can bepreferably selected from iodopropynyl butylcarbamate (CAS NO55406-53-6), aldicarb (CAS NO 116-06-3), carbofuran (CAS NO 1563-66-2)and mixtures thereof. The glyphosate biocide is preferably selected fromN-(phosphonomethyl)glycin (CAS NO 1071-83-6) and/orN-(phosphonomethyl)glycin in the form of the salt such as the ammoniumsalt or isopropylammonium salt (CAS NO 40465-66-5 and CAS NO38641-94-0).

The pyrithione biocide is preferably sodium pyrithione (CAS NO3811-73-2) and/or zinc pyrithione (CAS NO 13463-41-7).

For example, the dosage recommendation by commercial suppliers of such apyrithione biocide in the absence of a MIC reducing compound istypically from 600 to 1 500 ppm (w/w) active biocide per aqueouspreparation having a 75 wt.-% solids content of calcium carbonate.

The at least one biocide can be further preferably selected fromquaternary ammonium salts, peroxides, perchlorates, tributyl tin, heavymetals, biocidal enzymes, biocidal polypeptides, sulphonamides andmixtures thereof.

In one embodiment of the present invention, the at least one biocide isin an undiluted, i.e. concentrated form. In another embodiment of thepresent invention, the at least one biocide is diluted to a suitableconcentration before being contacted with the aqueous preparation instep d). In the diluted form, the at least one biocide is preferablydissolved in water, wherein the corresponding diluted compositioncomprises preferably up to 99.0 wt.-% of the at least one biocide, basedon the total weight of the composition. More preferably, the compositionin water comprises 1.0 to 95.0 wt.-% of the at least one biocide andmost preferably 1.0 to 85.0 wt.-% of the at least one biocide, based onthe total weight of the composition, whereby the composition may furthercomprise suitable stabilizers.

In one embodiment of the present invention, the at least one biocide isfree of aldehyde-releasing and/or aldehyde-based biocides in an amountof 250.0 to 5 000.0 ppm, calculated relative to the weight of water inthe preparation, when strains of bacteria which are resistant to,tolerant to and/or degrade aldehyde-releasing and/or aldehyde-basedbiocides are present in the aqueous preparation. Preferably, the atleast one biocide is free of aldehyde-releasing and/or aldehyde-based inan amount sufficient to be effective against strains of bacteria whichare resistant to, tolerant to and/or degrade aldehyde-releasing and/oraldehyde-based biocides in the aqueous preparation, when such strains ofbacteria are present in the aqueous preparation. Accordingly, also theaqueous preparation obtained after step d) and/or e) of the instantprocess is preferably free of aldehyde-releasing and/or aldehyde-basedbiocides in an amount of 250.0 to 5 000.0 ppm, calculated relative tothe weight of water in the preparation, when strains of bacteria whichare resistant to, tolerant to and/or degrade aldehyde-releasing and/oraldehyde-based biocides are present in the aqueous preparation. Morepreferably, the aqueous preparation obtained after step d) and/or e) ofthe instant process is free of aldehyde-releasing and/or aldehyde-basedbiocides in an amount sufficient to be effective against strains ofbacteria which are resistant to, tolerant to and/or degradealdehyde-releasing and/or aldehyde-based biocides in the aqueouspreparation, when such strains of bacteria are present in the aqueouspreparation.

Characterisation of Step c): Providing at Least One Water Soluble Sourceof Lithium Ions

According to step c) of the process of the present invention, at leastone water soluble source of lithium ions is provided.

The term “at least one” water soluble source of lithium ions in themeaning of the present invention means that the water soluble source oflithium ions comprises, preferably consists of, one or more watersoluble sources of lithium ions.

In one embodiment of the present invention, the at least one watersoluble source of lithium ions comprises, preferably consists of, onewater soluble source of lithium ions. Alternatively, the at least onewater soluble source of lithium ions comprises, preferably consists of,two or more water soluble sources of lithium ions. For example, the atleast one water soluble source of lithium ions comprises, preferablyconsists of, two or three water soluble sources of lithium ions.Preferably, the at least one water soluble source of lithium ionscomprises, preferably consists of, two or more water soluble sources oflithium ions.

It is appreciated that the at least one water soluble source of lithiumions provided in step c) of the instant process can be any lithiumion-comprising compound that is soluble in water. Accordingly, the term“water-soluble” lithium ion source or “soluble in water” in the meaningof the present invention refers to systems in which at least a part ofthe lithium ion source forms a solution with water, i.e. at least a partof the particles of the at least one source of lithium ions aredissolved in the solvent. In particular, the at least one source oflithium ions is considered as being “water-soluble” if at least a partof the at least one source of lithium ions provided in step c) formslithium ions which are dissolved in the water phase of the aqueouspreparation.

The term at least one water soluble “source of lithium ions” in themeaning of the present invention refers to a compound that compriseslithium ions, i.e. lithium cations.

In one embodiment of the present invention, the at least one watersoluble source of lithium ions is preferably provided in the form of atleast one lithium salt. Preferably the anionic group of the at least onelithium salt is selected from the group comprising carbonate, chloride,hydroxide, phosphate, citrate, maleate, acetate, lactate, sulphate,nitrate and mixtures thereof. In particular, the at least one lithiumsalt is selected from lithium carbonate, lithium chloride, lithiumhydroxide, lithium phosphate, lithium citrate, lithium maleate, lithiumacetate and lithium lactate are especially preferred as the MIC reducingcompound of the present invention.

For example, the at least one water soluble source of lithium ions ispreferably lithium carbonate (CAS NO. 554-13-2), lithium citrate (CASNO. 919-16-4) or lithium hydroxide (CAS NO. 1310-65-2).

In one embodiment of the present invention, the at least one watersoluble source of lithium ions is free of lithium fluoride. Accordingly,it is preferred that also the aqueous preparation obtained after step d)and/or e) of the instant process is/are free of lithium fluoride, i.e.fluoride ions.

It is to be noted that the aforementioned embodiment reflect the amountof fluoride ions being added via the at least one water soluble sourceof lithium ions to an aqueous preparation and does not cover anydissolved fluoride ions which may naturally be present in the aqueouspreparation. However, the amount of dissolved naturally occurringfluoride ions in, e.g. a calcium carbonate slurry usually is neglectableand well below 0.5 ppm, based on the pigment content of the slurry.

Additionally or alternatively, the at least one water soluble source oflithium ions can be introduced into the aqueous preparation via apolymeric salt of lithium, such as acrylic homopolymers, acryliccopolymers such as copolymers of acrylic acid and maleic acid and/oracrylamide, polyphosphates and mixtures thereof having multiple acidicsites which can be partially or totally neutralised with lithium ions.The polymeric salt of lithium is preferably selected fromLi₂Na₂polyphosphate, lithium-sodium hexamethaphosphate or lithiumpolyacrylate.

The polymeric salt of lithium which may be provided in step c) of theinstant invention is preferably partially or completely neutralized,preferably to a degree of 5.0 to 100.0%, preferably to a degree of 25.0to 100.0% and most preferably to a degree of 75.0 to 100.0% using aneutralizing agent containing ions of lithium and, optionally otheralkali metals and/or alkaline earth metals. In one embodiment the acidicsites of the polymeric salt of lithium are neutralized using aneutralizing agent containing only lithium. Neutralized polyacrylatesand/or polymethacrylates with an average molecular weight of not morethan 50 000, preferably with an average molecular weight in the rangefrom 1 000 to 25 000 and more preferably in the range from 3 000 to 12000 are especially suitable.

In general, the at least one water soluble source of lithium ions can beprovided in form of an aqueous solution, aqueous dispersion or a drymaterial. If the at least one water soluble source of lithium ions isprovided in form of an aqueous solution, the aqueous solution comprisesthe at least one water soluble source of lithium in an amount from 1.0to 45.0 wt.-%, preferably from 5.0 to 25.0 wt.-%, based on the totalweight of the aqueous solution.

If the at least one water soluble source of lithium ions is provided inform of an aqueous dispersion, the aqueous dispersion comprises the atleast one water soluble source of lithium in an amount from 1.0 to 60.0wt.-%, preferably from 5.0 to 50.0 wt.-% and more preferably from 15.0to 45.0 wt.-% based on the total weight of the aqueous dispersion.

Preferably, the at least one water soluble source of lithium ions isprovided in the form an aqueous solution.

Characterisation of Step d): Contacting the Aqueous Preparation with theat Least One Biocide

According to step d) of the process of the present invention, theaqueous preparation of step a) is contacted with the at least onebiocide of step b). It is one requirement of the instant invention thatthe at least one biocide of step b) is effective against at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould when present in the aqueous preparation.

It is thus appreciated that the at least one biocide is effectiveagainst at least one strain of bacteria and/or at least one strain ofyeast and/or at least one strain of mould in the aqueous preparationwhen the at least one biocide is present. This either prevents thegrowth or accumulation of the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould or leadsto a reduction of the cfu value (colony forming unit) in the treatedaqueous preparation.

In one embodiment of the present invention, the at least one strain ofbacteria is selected from the group consisting of gram-negativebacteria, gram-positive bacteria and mixtures thereof.

It is appreciated that gram-positive and gram-negative bacteria are wellknown in the art and are e.g. described in Biology of Microorganisms,“Brock”, Madigan M T, Martinko J M, Parker J, 1997, 8^(th) Edition. Inparticular, such bacteria represent evolutionary very distantly relatedclasses of bacteria each comprising of many bacterial families. Gramnegative bacteria are characterized by two membranes (outer and innermembrane) while gram positive bacteria contain only one membrane.Usually, the former contains a high amount of lipopolysaccharide and athin single-layer of peptidoglycan, while the latter has virtually nolipopolysaccharide, a multi-layered thick peptidocglycan and the coatcontains teichoic acids. For these differences the Gram positive andGram negative bacteria react differently on environmental influences.Methods for discriminating gram-positive and gram-negative bacteriainclude species identification by DNA sequencing techniques orbiochemical characterizations. Alternatively, the number of membranescan be determined directly by thin section transmission electronmicroscopy.

The term “at least one strain of bacteria” in the meaning of the presentinvention means that the strain of bacteria comprises, preferablyconsists of, one or more strains of bacteria.

In one embodiment of the present invention, the at least one strain ofbacteria comprises, preferably consists of, one strain of bacteria.Alternatively, the at least one strain of bacteria comprises, preferablyconsists of, two or more strains of bacteria. For example, the at leastone strains of bacteria comprises, preferably consists of, two or threestrains of bacteria. Preferably, the at least one strain of bacteriacomprises, preferably consists of, two or more strains of bacteria.

For example, the at least one strain of bacteria is selected from thegroup comprising Methylobacterium sp., Salmonella sp., Escherichia sp.such as Escherichia coli, Shigella sp., Enterobacter sp., Pseudomonassp. such as Pseudomonas mendocina, Bdellovibrio sp., Agrobacterium sp.,Alcaligenes sp., Flavobacterium sp., Rhizobium sp., Sphingobacteriumsp., Aeromonas sp., Chromobacterium sp., Vibrio sp., Hyphomicrobium sp.,Leptothrix sp., Micrococcus sp., Staphylococcus sp. such asStaphylococcus aureus, Agromyces sp., Acidovorax sp., and mixturesthereof.

For example, the at least one strain of bacteria is selected fromEscherichia sp. such as Escherichia coli, Staphylococcus sp. such asStaphylococcus aureus, and mixtures thereof. Additionally oralternatively, the at least one strain of yeast is selected from thegroup comprising Saccharomycotina, Taphrinomycotina,Schizosaccharomycetes, Basidiomycota, Agaricomycotina, Tremellomycetes,Pucciniomycotina, Microbotryomycetes, Candida sp. such as Candidaalbicans, Candida tropicalis, Candida stellatoidea, Candida glabrata,Candida krusei, Candida guilliermondii, Candida viswanathii, Candidalusitaniae and mixtures thereof Yarrowia sp. such as Yarrowialipolytica, Cryptococcus sp. such as Cryptococcus gattii andCryptococcus neofarmans, Zygosaccharomyces sp., Rhodotorula sp. such asRhodotorula mucilaginosa, and mixtures thereof.

The term “at least one strain of yeast” in the meaning of the presentinvention means that the strain of yeast comprises, preferably consistsof, one or more strains of yeast.

In one embodiment of the present invention, the at least one strain ofyeast comprises, preferably consists of, one strain of yeast.Alternatively, the at least one strain of yeast comprises, preferablyconsists of, two or more strains of yeast. For example, the at least onestrains of yeast comprises, preferably consists of, two or three strainsof yeast. Preferably, the at least one strain of yeast comprises,preferably consists of, two or more strains of yeast.

Additionally or alternatively, the at least one strain of mould isselected from the group comprising of Acremonium sp., Alternaria sp.,Aspergillus sp., Cladosporium sp., Fusarium sp., Mucor sp., Penicilliumsp., Rhizopus sp., Stachybotrys sp., Trichoderma sp., Dematiaceae sp.,Phoma sp., Eurotium sp., Scopulariopsis sp., Aureobasidium sp., Moniliasp., Botrytis sp., Stemphylium sp., Chaetomium sp., Mycelia sp.,Neurospora sp., Ulocladium sp., Paecilomyces sp., Wallemia sp.,Curvularia sp., and mixtures thereof.

The term “at least one strain of mould” in the meaning of the presentinvention means that the strain of mould comprises, preferably consistsof, one or more strains of mould.

In one embodiment of the present invention, the at least one strain ofmould comprises, preferably consists of, one strain of mould.Alternatively, the at least one strain of mould comprises, preferablyconsists of, two or more strains of mould. For example, the at least onestrains of mould comprises, preferably consists of, two or three strainsof mould. Preferably, the at least one strain of mould comprises,preferably consists of, two or more strains of mould.

It is preferred that the at least one biocide is effective against atleast one strain of bacteria and at least one strain of yeast and atleast one strain of mould when present in the aqueous preparation.

Alternatively, the at least one biocide is effective against at leastone strain of bacteria or at least one strain of yeast or at least onestrain of mould when present in the aqueous preparation.

Alternatively, the at least one biocide is effective against at leastone strain of bacteria and at least one strain of yeast or at least onestrain of mould when present in the aqueous preparation or the at leastone biocide is effective against at least one strain of bacteria or atleast one strain of yeast and at least one strain of mould when presentin the aqueous preparation.

In one embodiment of the present invention, the at least one biocide isfree of aldehyde-releasing and/or aldehyde-based biocides in an amountof 250.0 to 5 000.0 ppm, calculated relative to the weight of water inthe preparation, when strains of bacteria which are resistant to,tolerant to and/or degrade aldehyde-releasing and/or aldehyde-basedbiocides are present in the aqueous preparation. Preferably, the atleast one biocide is free of aldehyde-releasing and/or aldehyde-based inan amount sufficient to be effective against strains of bacteria whichare resistant to, tolerant to and/or degrade aldehyde-releasing and/oraldehyde-based biocides in the aqueous preparation, when such strains ofbacteria are present in the aqueous preparation.

In the meaning of the present invention, strains of bacteria which are“resistant to” refer to bacteria having the ability to withstand theeffects of aldehyde-releasing biocides and/or aldehyde-based biocideswhen dosed in an amount such that the total amount of thealdehyde-releasing biocides and/or aldehyde-based biocides in theaqueous preparation is from 250.0 ppm to 5 000.0 ppm, calculatedrelative to the amount of water in the preparation. In the meaning ofthe present invention, strains of bacteria which are “tolerant to” referto bacteria having the ability to survive in the presence of thealdehyde-releasing biocides and/or aldehyde-based biocides withoutevolving a random mutation. Strains of bacteria which “degrade” saidaldehyde-releasing biocides and/or aldehyde-based biocides in themeaning of the present invention correspond to bacteria having theability to convert said biocides into inactive forms and/or smallermolecules, e.g. by utilising these substrates as intermediates in theirpathways.

In general, the aqueous preparation of step a) and the at least onebiocide of step b) can be brought into contact by any conventional meansknown to the skilled person.

It is appreciated that contacting step d) is preferably carried out byadding the at least one biocide of step b) to the aqueous preparation ofstep a).

In one embodiment of the present invention, the step of contacting theaqueous preparation of step a) with the at least one biocide of step b)is carried out in that the at least one biocide is added to the aqueouspreparation under mixing. A sufficient mixing may be achieved by shakingthe aqueous preparation or by agitation, which may provide a morethorough mixing. In one embodiment of the present invention, contactingstep d) is carried out under agitation to ensure a thorough mixing ofthe aqueous preparation and the at least one biocide. Such agitation canbe carried out continuously or discontinuously.

According to the present invention, the aqueous preparation is contactedwith the at least one biocide such that the at least one biocide ispresent in the water phase of the aqueous preparation in an amount offrom 0.4 to 6 500.0 ppm, calculated relative to the weight of water inthe aqueous preparation.

For example, contacting step d) is carried out in that the at least onebiocide is added to the aqueous preparation in an amount of from 0.5 ppmto 6 000.0 ppm, calculated relative to the weight of water in theaqueous preparation.

Additionally or alternatively, contacting step d) is carried out in thatthe at least one biocide is added to the aqueous preparation in anamount being at least 9% below the minimum inhibitory concentration(MIC) of the at least one biocide being effective against the at leastone strain of bacteria and/or at least one strain of yeast and/or atleast one strain of mould in the absence of the MIC reducing compound,i.e. the at least one water soluble source of lithium ions.

For example, contacting step d) is carried out in that the at least onebiocide is added to the aqueous preparation in an amount being at least33%, more preferably at least 50% and most preferably at least 75%,below the minimum inhibitory concentration (MIC) of the at least onebiocide for the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould in the absence ofthe MIC reducing compound, i.e. the at least one water soluble source oflithium ions.

In one embodiment of the present invention, the aqueous preparation iscontacted with the at least one biocide such that the at least onebiocide is present in the water phase of the aqueous preparation in anamount of from 0.4 to 6 500.0 ppm, preferably of from 0.5 ppm to 6 000.0ppm, calculated relative to the weight of water in the aqueouspreparation and such that the at least one biocide is added to theaqueous preparation in an amount being at least 9%, preferably at least33%, more preferably at least 50% and most preferably at least 75%,below the minimum inhibitory concentration (MIC) of the at least onebiocide for the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould in the absence ofthe MIC reducing compound, i.e. the at least one water soluble source oflithium ions.

It is appreciated that contacting step d) can be repeated one or moretimes.

The aqueous preparation obtained in step d) preferably has solidscontent corresponding to the solids content of the aqueous preparationprovided in step a). It is thus appreciated that the aqueous preparationobtained in step d) preferably has solids content of up to 85.0 wt.-%.For example, the solids content of the aqueous preparation obtained instep d) is from 10.0 to 82.0 wt.-%, and more preferably from 20.0 to80.0 wt.-%, based on the total weight of the aqueous preparationobtained in step d).

Additionally or alternatively, the pH of the aqueous preparationobtained in step d) preferably corresponds to the pH of the aqueouspreparation provided in step a). It is thus appreciated that the aqueouspreparation obtained in step d) preferably has a pH value of from 2 to12. For example, the aqueous preparation obtained in step d) has a pHvalue of from 6 to 12 and more preferably from 7 to 10.5.

Typically, the aqueous preparations obtained in step d) has a viscositybeing preferably in the range between 50 to 2 000 mPa·s and preferably80 to 800 mPa·s, as measured with a Brookfield DV-II Viscometer at aspeed of 100 rpm and equipped with a LV-3 spindle.

Characterisation of Step e): Contacting the Aqueous Preparation with theat Least One Water Soluble Source of Lithium Ions

According to step e) of the process of the present invention, theaqueous preparation of step a) is contacted before and/or during and/orafter step d) with the at least one water soluble source of lithium ionsof step c).

The aqueous preparation of step a) and the at least one water solublesource of lithium ions of step c) can be brought into contact by anyconventional means known to the skilled person.

It is appreciated that contacting step e) is preferably carried out byadding the at least one water soluble source of lithium ions of step c)to the aqueous preparation of step a) before and/or during and/or afteradding the at least one biocide of step b) to the aqueous preparation ofstep a).

For example, at least one water soluble source of lithium ions ispreferably added into the aqueous preparation by mixing. A sufficientmixing may be achieved by shaking or by agitation, which may provide amore thorough mixing. In one embodiment of the present invention,contacting step e) is carried out under agitation to ensure a thoroughmixing of the aqueous preparation and the at least one water solublesource of lithium ions. Such agitation can be carried out continuouslyor discontinuously.

In one embodiment of the present invention, the step of contacting theaqueous preparation of step a) with the at least one water solublesource of lithium ions of step c) is carried out in that the at leastone water soluble source of lithium ions is added to the aqueouspreparation before and during and after adding the at least one biocideto the aqueous preparation.

Alternatively, contacting step e) is carried out by adding the at leastone water soluble source of lithium ions of step c) to the aqueouspreparation before and after adding the at least one biocide to theaqueous preparation. Alternatively, contacting step e) is carried out byadding the at least one water soluble source of lithium ions of step c)to the aqueous preparation before and during adding the at least onebiocide to the aqueous preparation. Alternatively, contacting step e) iscarried out by adding the at least one at least one water soluble sourceof lithium ions of step c) to the aqueous preparation during and afteradding the at least one biocide to the aqueous preparation.

In case the at least one water soluble source of lithium ions of step c)is added to the aqueous preparation before and during and after orbefore and during or during and after or before and after adding the atleast one biocide to the aqueous preparation, the at least one watersoluble source of lithium ions of step c) is preferably added in severalportions and/or continuously over the period required for contacting theaqueous preparation with the at least one water soluble source oflithium ions of step c).

If the at least one water soluble source of lithium ions of step c) isadded in several portions, the at least one water soluble source oflithium ions of step c) can be added in about equal portions or unequalportions to the aqueous preparation.

In one embodiment of the present invention, contacting step e) iscarried out in that the at least one water soluble source of lithiumions of step c) is added to the aqueous preparation of step a) before orduring or after adding the at least one biocide to the aqueouspreparation.

For example, contacting step e) is carried out by adding the at leastone water soluble source of lithium ions of step c) to the aqueouspreparation before or during adding the at least biocide to the aqueouspreparation. Alternatively, contacting step e) is carried out by addingthe at least one water soluble source of lithium ions of step c) to theaqueous preparation before or after adding the at least one biocide tothe aqueous preparation. Alternatively, contacting step e) is carriedout by adding the at least one water soluble source of lithium ions ofstep c) to the aqueous preparation during or after adding the at leastone biocide to the aqueous preparation.

In one embodiment of the present invention, contacting step e) iscarried out by adding the at least one water soluble source of lithiumions of step c) to the aqueous preparation before adding the at leastone biocide to the aqueous preparation. Alternatively, contacting stepe) is carried out by adding the at least one water soluble source oflithium ions of step c) to the aqueous preparation during adding the atleast one biocide to the aqueous preparation. Alternatively, contactingstep e) is carried out by adding the at least one water soluble sourceof lithium ions of step c) to the aqueous preparation after adding theat least one biocide to the aqueous preparation.

For example, contacting step e) is carried out by adding the at leastone water soluble source of lithium ions of step c) to the aqueouspreparation before adding the at least one biocide to the aqueouspreparation. Thus, it is preferred that contacting step e) is carriedout before contacting step d).

Alternatively, the at least one water soluble source of lithium ions ofstep c) is added to the aqueous preparation in combination with the atleast one biocide of step b) as finished mixture. Accordingly, the atleast one water soluble source of lithium ions of step c) is preferablyadded to the aqueous preparation during contacting step d) is carriedout.

In this embodiment, contacting step e) of the instant process ispreferably carried out by adding a finished mixture comprising the atleast one water soluble source of lithium ions of step c) and the atleast one biocide of step b) to the aqueous preparation of step a).

If the at least one biocide of step b) and the at least one watersoluble source of lithium ions of step c) are provided in form amixture, the mixture can be present in any appropriate form, e.g. in theform of a dry material or in the form of an aqueous solution.

If the at least one water soluble source of lithium ions of step c) isadded to the aqueous preparation before or during or after adding the atleast one biocide to the aqueous preparation, the at least one watersoluble source of lithium ions is preferably added in one portion and/orcontinuously before or during or after adding the at least one biocideto the aqueous preparation.

Accordingly, the at least one biocide and the at least one water solublesource of lithium ions can be added separately (first the at least onebiocide and then the at least one water soluble source of lithium ionsor vice versa) or simultaneously (e.g. as an aqueous mixture) to theaqueous preparation. Furthermore, the at least one biocide and/or the atleast one water soluble source of lithium ions can be added once orseveral times, e.g. in specific time intervals, to the aqueouspreparation. Preferably, the at least one water soluble source oflithium ions is added once and the at least one biocide is added once orseveral times, e.g. in specific time intervals, to the aqueouspreparation.

It is appreciated that contacting step e) can be repeated one or moretimes.

It is one requirement of the present invention that the at least onewater soluble source of lithium ions of step c) is present in the waterphase of the aqueous preparation such that the total amount of lithiumions is from 15.0 to 800.0 mMol/L, calculated relative to the weight ofwater in the aqueous preparation. For example, the at least one watersoluble source of lithium ions of step c) is present in the water phaseof the aqueous preparation such that the total amount of lithium ions isfrom 15.0 to 700.0 mMol/L, calculated relative to the weight of water inthe aqueous preparation. In one embodiment of the present invention, theat least one water soluble source of lithium ions of step c) is presentin the water phase of the aqueous preparation such that the total amountof lithium ions is from 15.0 to 600.0 mMol/L, calculated relative to theweight of water in the aqueous preparation.

It is to be noted that the aforementioned figures reflect the amount oflithium ions being added via the at least one water soluble source oflithium ions to an aqueous preparation as MIC reducing compound and donot cover any dissolved lithium ions which may naturally be present inthe aqueous preparation. However, the amount of dissolved naturallyoccurring lithium ions in e.g. calcium carbonate slurry usually isneglectable and well below 50.0 ppm, based on the pigment content of theslurry.

The amount of the at least one water soluble source of lithium ionsadded to the aqueous preparation can be individually adjusted dependingon the at least one biocide to be added into the aqueous preparation. Inparticular, the amount of the at least one water soluble source oflithium ions depends on the nature and the occurrence of the at leastone biocide to be used in the aqueous preparation. The optimum amount tobe employed within the defined ranges can be determined by preliminarytests and test series on a laboratory scale and by supplementaryoperational tests.

In accordance with the present invention, the lithium ions of the atleast one water soluble source of lithium ions act as MIC reducingcompound and thus the instant process is suitable for reducing theminimum inhibitory concentration (MIC) of a biocide against at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould in the aqueous preparation.

In particular, the aqueous preparation is contacted with the at leastone water soluble source of lithium ions in an amount such that theminimum inhibitory concentration

(MIC) of the at least one biocide against the at least one strain ofbacteria and/or at least one strain of yeast and/or at least one strainof mould fulfils the equation (I)MIC_(withoutLi)/MIC_(Li)≥1.1  (I)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm, calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm, calculatedrelative to the weight of water in the aqueous preparation of step a).

In one embodiment of the present invention, contacting step e) iscarried out such that the minimum inhibitory concentration (MIC) of theat least one biocide against the at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould fulfilsthe equation (Ia), preferably equation (Ib) and most preferably equation(Ic)MIC_(withoutLi)/MIC_(Li)≥1.5  (Ia)MIC_(withoutLi)/MIC_(Li)≥2.0  (Ib)MIC_(withoutLi)/MIC_(Li)≥4.0  (Ic)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of thebiocide against the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould without the at leastone water soluble source of lithium ions in ppm calculated relative tothe weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the biocideagainst the at least one strain of bacteria and/or at least one strainof yeast and/or at least one strain of mould with the at least one watersoluble source of lithium ions in ppm calculated relative to the weightof water in the aqueous preparation of step a).

For example, contacting step e) is carried out such that the minimuminhibitory concentration (MIC) of the at least one biocide against theat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould fulfils the equation (II),preferably the equation (IIa), more preferably equation (IIb) and mostpreferably equation (IIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (II)1.1≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIa)1.1≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIb)1.1≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

In one embodiment of the present invention, contacting step e) iscarried out such that the minimum inhibitory concentration (MIC) of theat least one biocide against the at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould fulfilsthe equation (III), preferably the equation (IIIa), more preferablyequation (IIIb) and most preferably equation (IIIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (III)1.5≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIIa)2.0≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIIb)4.0≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

It is to be understood that the amount of the at least one water solublesource of lithium ions according to the present invention is selectedsuch that it is in combination with the at least one biocide in theaqueous preparation sufficient, i.e. high enough for reducing theminimum inhibitory concentration (MIC) of a biocide against at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould in an aqueous preparation. In other words, by usingthe inventive process the minimum inhibitory concentration (MIC) of abiocide is reduced such that the amount of the at least one biocide inthe aqueous preparation can be significantly reduced in order to provideefficient biocidal activity.

It is thus appreciated that the aqueous preparation of the presentinvention comprises lithium ions. The aqueous preparation is preferablyobtainable by the process of the instant invention, i.e. the process forreducing the minimum inhibitory concentration (MIC) of a biocide againstat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould in an aqueous preparation.

The lithium ions of the at least one water soluble source of lithiumions are considered as MIC reducing compound. It is thus required thatthe aqueous preparation comprises the lithium ions such that the totalamount of lithium ions in the water phase is from 15.0 to 800.0 mMol/L,more preferably from 15.0 to 700.0 mMol/L and most preferably from 15.0to 600.0 mMol/L, calculated relative to the weight of water in theaqueous preparation.

Additionally, the aqueous preparation comprises at least one biocidebeing effective against at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould. Preferably, theaqueous preparation comprises the at least one biocide such that itstotal amount in the water phase is from 0.4 to 6 500.0 ppm, preferablyfrom 0.5 ppm to 6 000.0 ppm, calculated relative to the weight of waterin the aqueous preparation.

With regard to the definition of the at least one biocide, the at leastone strain of bacteria and/or at least one strain of yeast and/or atleast one strain of mould and preferred embodiments thereof, referenceis made to the statements provided above when discussing the technicaldetails of the process of the present invention.

In one embodiment of the present invention, the aqueous preparation ofthe instant process is free of aldehyde-releasing and/or aldehyde-basedbiocides in an amount of 250.0 to 5 000.0 ppm, calculated relative tothe weight of water in the preparation, when strains of bacteria whichare resistant to, tolerant to and/or degrade aldehyde-releasing and/oraldehyde-based biocides are present in the aqueous preparation.Preferably, the aqueous preparation of the instant process is free ofaldehyde-releasing and/or aldehyde-based biocides in an amountsufficient to be effective against strains of bacteria which areresistant to, tolerant to and/or degrade aldehyde-releasing and/oraldehyde-based biocides in the aqueous preparation, when such strains ofbacteria are present in the aqueous preparation.

As already mentioned above, the lithium ions of the at least one watersoluble source of lithium ions effect a reduction of the minimuminhibitory concentration of the at least one biocide being effectiveagainst at least one strain of bacteria and/or at least one strain ofyeast and/or at least one strain of mould in the aqueous preparation.

Thus, the aqueous preparation comprises the at least one biocide in anamount being below the minimum inhibitory concentration (MIC) of thesame biocide in the absence of lithium ions.

It is thus appreciated that the instant the aqueous preparationcomprises the at least one biocide in an amount being at least 9%,preferably at least 33%, more preferably at least 50% and mostpreferably at least 75%, below the minimum inhibitory concentration(MIC) of the at least one biocide being effective against the at leastone strain of bacteria and/or at least one strain of yeast and/or atleast one strain of mould in the absence of the MIC reducing compound,i.e. the at least one water soluble source of lithium ions.

Accordingly, it is one specific finding of the instant aqueouspreparation that it comprises the at least one biocide in an amount suchthat the minimum inhibitory concentration (MIC) of the at least onebiocide against the at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould fulfils the equation(I)MIC_(withoutLi)/MIC_(Li)≥1.1  (1)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe water soluble lithium ions in ppm, calculated relative to the weightof water in the aqueous preparation,MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the watersoluble lithium ions in ppm, calculated relative to the weight of waterin the aqueous preparation.

Preferably, the aqueous preparation comprises the at least one biocidein an amount such that the minimum inhibitory concentration (MIC) of theat least one biocide against the at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould fulfilsthe equation (Ia), preferably equation (Ib) and most preferably equation(Ic)MIC_(withoutLi)/MIC_(Li)≥1.5  (Ia)MIC_(withoutLi)/MIC_(Li)≥2.0  (Ib)MIC_(withoutLi)/MIC_(Li)≥4.0  (Ic)whereinMIC_(without) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe water soluble lithium ions in ppm, calculated relative to the weightof water in the aqueous preparation,MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the watersoluble lithium ions in ppm, calculated relative to the weight of waterin the aqueous preparation.

For example, the aqueous preparation comprises the at least one biocidein an amount such that the minimum inhibitory concentration (MIC) of theat least one biocide against the at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould fulfilsthe equation (II), preferably the equation (IIa), more preferablyequation (IIb) and most preferably equation (IIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (II)1.1≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIa)1.1≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIb)1.1≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

In one embodiment of the present invention, the aqueous preparationcomprises the at least one biocide in an amount such that the minimuminhibitory concentration (MIC) of the at least one biocide against theat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould fulfils the equation (III),preferably the equation (IIIa), more preferably equation (IIIb) and mostpreferably equation (IIIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (III)1.5≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIIa)2.0≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIIb)4.0≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

The liquid phase of the aqueous preparation comprises, preferablyconsists of, water. In one embodiment of the present invention, theaqueous preparation comprises an organic solvent selected from the groupcomprising alcohols such as methanol, ethanol, isopropanol,carbonyl-group containing solvents such as ketones, e.g. acetone oraldehydes, esters such as isopropyl acetate, carboxylic acids such asformic acid, sulfoxidess such as dimethyl sulfoxide and mixturesthereof. If the aqueous preparation comprises an organic solvent, theaqueous preparation comprises the organic solvent in an amount up to40.0 wt.-% preferably from 1.0 to 30.0 wt.-% and most preferably from1.0 to 25.0 wt.-%, based on the total weight of the liquid phase of theaqueous preparation. For example, the liquid phase of the aqueouspreparation consists of water. If the liquid phase of the aqueouspreparation consists of water, the water can be any water such as tapwater and/or deionised water.

The aqueous preparation preferably comprises at least one inorganicparticulate material and/or at least one organic material.

With regard to the definition of the at least one inorganic particulatematerial, at least one organic material and preferred embodimentsthereof, reference is made to the statements provided above whendiscussing the technical details of the process of the presentinvention.

Thus, the aqueous preparation is preferably an aqueous slurry.

The aqueous preparation preferably has solids content of up to 85.0wt.-%. For example, the solids content of the aqueous preparation isfrom 10.0 to 82.0 wt.-%, and more preferably from 20.0 to 80.0 wt.-%,based on the total weight of the aqueous preparation.

The aqueous preparation preferably has a pH value of from 2 to 12. Forexample, the aqueous preparation has a pH value of from 6 to 12 and morepreferably from 7 to 10.5.

Typically, the aqueous preparation has a viscosity being preferably inthe range between 50 to 800 mPa's and preferably 80 to 600 mPa·s, asmeasured with a Brookfield DV-II Viscometer at a speed of 100 rpm andequipped with a LV-3 spindle.

The inventive process or aqueous preparation thus provides a number ofimproved properties. First of all, the addition of a specific amount oflithium ions in form of a at least one water soluble source of lithiumions reduces the minimum inhibitory concentration (MIC) of the at leastone biocide being effective against at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mouldwhen present in an aqueous preparation in comparison to the minimuminhibitory concentration (MIC) of the same biocide in the absence of thelithium ions. The lithium ions of the at least one water soluble sourceof lithium ions thus act as MIC reducing compound. The inventive processthus allows for the reduction of the biocide concentration in an aqueouspreparation maintaining and/or improving the biocidal activity.

The addition of lithium ions in the inventive process or compositionsresults in a reduced or prevented growth and accumulation of at leastone strain of bacteria and/or at least one strain of yeast and/or atleast one strain of mould in the aqueous preparation and the tendency ofalterations of these preparations is reduced, while low viscosity, thebrilliance of the colour and the odour quality of the preparations canbe maintained. Furthermore, the stabilisation of such preparationsagainst attack and destruction by at least one strain of bacteria and/orat least one strain of yeast and/or at least one strain of mould in anaqueous preparation, results in a good microbiological quality of thepreparations.

In accordance with the present invention, the at least one water solublesource of lithium ions is used as MIC reducing compound. The MICreducing compound referred to herein is a compound which is capable ofreducing the minimum inhibitory concentration (MIC) of a biocide againstat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould in an aqueous preparation relativeto an aqueous preparation having no such MIC reducing compound. In otherwords, the lithium ions of the at least one water soluble source oflithium ions, used according to the present invention in combinationwith the at least one biocide, reduce the minimum inhibitoryconcentration (MIC) of the biocide in the aqueous preparation.

In view of the goods results obtained, the present invention refers in afurther aspect to the use of a water soluble source of lithium ions forreducing the minimum inhibitory concentration (MIC) of a biocide againstat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould in an aqueous preparation. It isappreciated that the reduction is achieved when the minimum inhibitoryconcentration (MIC) of the at least one biocide against the at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould

fulfils the equation (I), preferably the equation (Ia), more preferablyequation (Ib) and most preferably equation (Ic)MIC_(withoutLi)/MIC_(Li)≥1.1  (I)MIC_(withoutLi)/MIC_(Li)≥1.5  (Ia)MIC_(withoutLi)/MIC_(Li)≥2.0  (Ib)MIC_(withoutLi)/MIC_(Li)≥4.0  (Ic)whereinMIC_(witoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

Preferably, the reduction is achieved when the minimum inhibitoryconcentration (MIC) of the at least one biocide against the at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould fulfils the equation (II), preferably the equation(IIa), more preferably equation (IIb) and most preferably equation (IIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (II)1.1≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIa)1.1≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIb)1.1≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

More preferably, the reduction is achieved when the minimum inhibitoryconcentration (MIC) of the at least one biocide against the at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould fulfils the equation (III), preferably the equation(IIIa), more preferably equation (IIIb) and most preferably equation(IIIc)1.1≤MIC_(withoutLi)/MIC_(Li)≤30.0  (III)1.5≤MIC_(withoutLi)/MIC_(Li)≤25.0  (IIIa)2.0≤MIC_(withoutLi)/MIC_(Li)≤20.0  (IIIb)4.0≤MIC_(withoutLi)/MIC_(Li)≤10.0  (IIIc)whereinMIC_(withoutLi) is the minimum inhibitory concentration (MIC) of the atleast one biocide against the at least one strain of bacteria and/or atleast one strain of yeast and/or at least one strain of mould withoutthe at least one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a),MIC_(Li) is the minimum inhibitory concentration (MIC) of the at leastone biocide against the at least one strain of bacteria and/or at leastone strain of yeast and/or at least one strain of mould with the atleast one water soluble source of lithium ions in ppm calculatedrelative to the weight of water in the aqueous preparation of step a).

With regard to the definition of the at least one water soluble sourceof lithium ions, aqueous preparation, at least one biocide, at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould and preferred embodiments thereof, reference is madeto the statements provided above when discussing the technical detailsof the process of the present invention.

The following examples may additionally illustrate the invention, butare not meant to restrict the invention to the exemplified embodiments.The examples below show the good microbiological stability of theaqueous preparations of minerals, pigments or fillers protected with thecomposition according to the present invention:

EXAMPLES Measurement Processes

The following measurement processes were used to evaluate the parametersgiven in the examples and claims.

BET Specific Surface Area of a Material

The BET specific surface area was measured via the BET process accordingto ISO 9277 using nitrogen.

Particle Size Distribution (Mass % Particles with a Diameter <X) andWeight Median Diameter (D₅₀) of a Particulate Material

Weight median grain diameter and grain diameter mass distribution of aparticulate material were determined via the sedimentation process, i.e.an analysis of sedimentation behaviour in a gravitational field. Themeasurement was made with a Sedigraph™ 5100 of Micromeritics InstrumentCorporation.

The method and the instrument are known to the skilled person and arecommonly used to determine grain size of fillers and pigments. Themeasurement is carried out in an aqueous solution of 0.1 wt % Na₄P₂O₇.The samples are dispersed using a high speed stirrer and supersonics.

pH Measurement

The pH of the water samples is measured by using a standard pH-meter atapproximately 25° C.

Brookfield-Viscosity

All Brookfield-viscosities are measured with a Brookfield DV-IIViscometer equipped with a LV-3 spindle at a speed of 100 rpm and roomtemperature

(20±3° C.).

Amounts of Biocide and Lithium

All biocide and lithium amounts quoted in ppm represent mg values perkilogram of water in the aqueous preparation. Lithium ion concentrationsare further quoted in mMol/L (millimol per litre) or mM (millimolar)according to the International System of Units in the water of theaqueous preparation.

Bacterial Count

When not otherwise indicated, the quoted bacterial counts (values are incfu/plate) in the Tables here below are determined after 2 daysfollowing plate-out and incubation at 30° C. The counting method was asfollows. The aqueous preparations were stirred well with a cotton swap(e.g. Applimed SA, No. 1102245); the excess aqueous preparation wasremoved by dipping it gently to the side of the aqueous preparationcontainer, leaving approximately 200 mg of aqueous preparation on theswap. Then three even streaks were made on a tryptic soy agar plate(TSA, prepared using BD 236950) from right to left and three more fromtop to bottom. TSA plates were then incubated for 48 h at 30° C. Colonyforming units (cfu) were then counted and reported as cfu/plate. Countsfrom 100 to 999 cfu per plate are reported as ≥100 cfu/plate. Counts of1000 cfu and above per plate are reported as ≥1000 cfu/plate. Yeast andmoulds were counted as described for bacteria with the followingexceptions, a) Sabouraud Dextrose Agar (SDA) containing Chloramphenicol(e.g. heipha Dr. Müller GmbH, No. 1460030020) were used instead of TSA,b) SDA plates were incubated at 25° for 5 days and c) cfu were countedand reported after 48 h and 5 days of incubation. Yeast and mouldscounts from 20 to 99 cfu per plate are reported as ≥20 cfu/plate. Yeastand moulds counts of 100 cfu and above per plate are reported as ≥100cfu/plate.

Solids Content

The solids content is measured using a Moisture Analyzer ofMettler-Toledo MJ33. The method and the instrument are known to theskilled person.

Minimum Inhibitory Concentration (MIC)

For determining the MIC, the tested microorganism, i.e. the strain ofbacteria and/or strain of yeast and/or strain of mould, were freshlygrown until the end of the logarithmic growth phase according to therequirements of the individual species to a density of approximately10⁷-10⁹ cells/ml.

For example, fresh bacteria cultures of the bacteria E. coli, e.g. E.coli ATCC 11229, and S. aureus, e.g. S. aureus strains DSMZ 346, wereprepared by inoculation of 3 ml liquid growth media (tryptic soy broth,e.g. Fluka Cat. No. 22092) from a stock culture and incubation for 16 to20 h at 30° C. with agitation at 150 rotations per minutes (rpm) leadingto a cell density of approximately 2×10⁸ cells/ml. Fresh cultures ofresistant bacteria, adapted to the conditions in biocide containingCaCO₃ slurries, were prepared by inoculation of 50 g 75 wt.-% solidcontent CaCO₃ slurry from a stock culture and incubated for 14 to 28days at 30° C. without agitation. The slurry contained the correspondingbiocides to which the strains are resistant at the concentrationsdescribed herebelow. rOmyAK, is a Pseudomonas mendocina strain resistantto a biocide mixture of 750 ppm 1,6-Dihydroxy-2,5-dioxane (CAS NO.3586-55-8) and 19 ppm CMIT/MIT (CAS NO. 55965-84-9). rOPP, is aPseudomonas mendocina strain resistant to 660 ppm 2-phenylphenol (OPP)(CAS NO 90-43-7). rGDA/IT, is a Pseudomonas mendocina strain resistantto a biocide mixture of 340 ppm glutaraldehyde (CAS NO. 111-30-8) and 20ppm CMIT/MIT (CAS NO. 55965-84-9).

Lithium ions were added to the aqueous preparation (e.g. CaCO₃ slurry)by the addition of a water soluble lithium salt. For example to 50 gCaCO₃ slurry with a solid content of 75% (w/w) 1.177 ml of a 74 g/lLi₂CO₃ suspension was added and mixed well leading to a lithium ionconcentration of 172 mM or 1205 ppm in the water phase. As anotherexample to 50 g CaCO₃ slurry with a solid content of 75 wt.-% (w/w) 0.04ml of a 292 g/L Li₃Citrate (2M) solution was added and mixed wellleading to a lithium ion concentration of 19 mM or 135 ppm in the waterphase.

The biocide to be tested was added to the aqueous preparation (e.g.CaCO₃ slurry with or without lithium ions) in increasing concentrationsstarting from 0 ppm (without biocide). The concentrations ranged fromconcentrations higher than recommended by the supplier, to very lowamounts (as low as 1 ppm or lower). Of each biocide concentration a 3 mlsample of aqueous preparation was combined with 20 μl fresh bacterialculture.

If a curative MIC was tested, the bacteria were added to the aqueouspreparation before the biocide and the lithium was added, using 20 μl ofa fresh bacterial culture per 3 ml of aqueous preparation or 0.1 ml of afresh culture of resistant bacteria from a slurry per 3 ml of aqueouspreparation.

All samples were incubated at 30° C. for 24 h. After incubation colonyforming units (cfu) per plate (cfu/plate) were determined as describedabove under bacterial count.

The MIC for bacteria is defined as the lowest concentration of biocidein the presence or absence of lithium ion amongst all samples tested,where the bacterial concentration dropped below 100 cfu/plate. The MICfor yeast and mould is defined as the lowest concentration of biocide inthe presence or absence of lithium ion amongst all samples tested, wherethe microbial concentration dropped below 20 cfu/plate. The test wasvalid only, if the sample without biocide showed more than 100 cfu/platefor bacteria and more than 20 cfu/plate for yeast and mould. If none ofthe samples containing the respective biocide dropped below 100cfu/plate for bacteria and below 20 cfu/plate for yeast and mould theMIC was reported as >highest biocide concentration tested (e.g. >1000ppm).

Example 1 Preparation of Calcium Carbonate Slurries

An aqueous slurry of calcium carbonate (Italian marble; d₅₀=10 μm; 21wt.-%<2 μm) was prepared at 75 wt.-% solid content. The slurry was wetground at 95° C. using 0.6 wt.-% in respect to dry solids material of asodium/calcium neutralized polyacrylate grinding agent (Mw 6 000) in a200 l vertical ball mill to a final particle size distribution ofd₅₀=0.7 μm; 90 wt.-%<2 μm.

Example 2 MIC Determination and Reduction

The determination of the minimum inhibitory concentration (MIC) forvarious biocides in the absence of lithium ions and the correspondingMIC reduction of the respective biocide in the presence of lithium ionsagainst strains of various bacterial species are summarized in Tables 1to 4 here below. The tests were carried out with differing biocideconcentrations at constant lithium ion concentration. Numbers indicatecfu/plate.

TABLE 1 Testing the MIC of MIT (CAS NO 2682-20-4) in the presence andabsence of lithium ions against the bacterial strain rOmy AK no 18 ppm35 ppm 106 ppm rOmy AK MIT MIT MIT MIT 329 mM Li⁺ ≥1000 ≥100 68 0 no Li⁺≥1000 ≥1000 ≥100 0

The MIC for bacteria was defined as the lowest concentration of biocidein the presence or absence of lithium ions amongst all samples tested,where the bacterial concentration dropped below 100 cfu/plate. As can begathered from Table 1, the minimum inhibitory concentration (MIC) of MITagainst the rOmy AK strain is clearly above 35 ppm MIT when the biocideis implemented alone at the listed amount, i.e. in the absence oflithium ions, the MIC_(withoutLi) is 106 ppm. The results also show thatwhen lithium ions are provided alone via the addition of Li₂CO₃, theyhave no antimicrobial effect on the rOmy AK strain. However, if thebiocide is implemented in combination with lithium ions, the MIC_(Li) ofMIT against the rOmy AK strain is reduced to 35 ppm MIT.

TABLE 2 Testing the MIC of 4-chloro-3-methylphenol (CAS NO 59-50-7) inthe presence and absence of lithium ions against the bacterial E. colistrain ATCC11229 88.5 ppm 177 ppm 354 ppm no 4-chloro-3- 4-chloro-3-4-chloro-3- E. coli 4-chloro-3- methyl- methyl- methyl- ATCC11229 phenolmethylphenol phenol phenol 197 mM/Li⁺ ≥100 ≥100 23 0 no Li⁺ ≥1000 ≥1000≥100 0

As can be gathered from Table 2, the minimum inhibitory concentration(MIC) of 4-chloro-3-methylphenol against the E. coli strain is clearlyabove 177 ppm 4-chloro-3-methylphenol when the biocide is implementedalone at the listed amount, i.e. in the absence of lithium ions, theMIC_(withoutLi) is 354 ppm. The results also show that when lithium ionsare provided alone via the addition of Li₂CO₃, they have noantimicrobial effect on the E. coli strain. However, if the biocide isimplemented in combination with lithium ions, the MIC_(Li) of4-chloro-3-methylphenol against the E. coli strain is reduced to 177 ppm4-chloro-3-methylphenol.

TABLE 3 Testing the MIC of a CMIT/MIT (CAS NO. 55965-84-9) mixture(weight ratio: 3:1) in the presence and absence of lithium ions againstthe bacterial S. aureus strain DSMZ 346 S. aureus no 7 ppm 14 ppm 28 ppmDSMZ 346 CMIT/MIT CMIT/MIT CMIT/MIT CMIT/MIT 197 mM Li⁺ ≥1000 30 0 0 noLi⁺ ≥1000 ≥100 ≥100 87

As can be gathered from Table 3, the minimum inhibitory concentration(MIC) of CMIT/MIT against the S. aureus strain is clearly above 14 ppmCMIT/MIT when the biocide is implemented alone at the listed amount,i.e. in the absence of lithium ions, the MIC_(withoutLi) is 28 ppm. Theresults also show that when lithium ions are provided alone via theaddition of Li₂CO₃, they have no antimicrobial effect on the S. aureusstrain. However, if the biocide is implemented in combination withlithium ions, the MIC_(Li) of CMIT/MIT against the S. aureus strain isreduced to 7 ppm CMIT/MIT.

TABLE 4 Testing the MIC of a Sodium pyrithione (CAS NO 3811-73-2) in thepresence and absence of lithium ions against the bacterial S. aureusstrain DSMZ 346 Sodium pyrithione S. aureus 300 900 DSMZ 346 no 75 ppm150 ppm ppm 600 ppm ppm 96 mM ≥1000 ≥100 93 12 0 0 no Li⁺ ≥1000 ≥1000≥100 ≥100 ≥100 ≥100

As can be gathered from Table 4, the minimum inhibitory concentration(MIC) of sodium pyrithione against the S. aureus strain is clearly above900 ppm sodium pyrithione when the biocide is implemented alone at thelisted amount, i.e. in the absence of lithium ions, the MIC_(withoutLi)is >900 ppm. The results also show that when lithium ions are providedalone via the addition of lithium citrate, they have no antimicrobialeffect on the S. aureus strain. However, if the biocide is implementedin combination with these lithium ions, the MIC_(Li) of sodiumpyrithione against the S. aureus strain is reduced to 150 ppm sodiumpyrithione.

Example 3 MIC Reduction for Various Biocides

The MIC reduction of the tested biocides in the presence of lithium ionsagainst strains of various bacterial species are summarized in Table 5here below. The tests were carried out with differing biocideconcentrations, differing lithium ion concentrations and differingsources of lithium ions as described in the Table 5.

It is shown in Table 5 that the presence of lithium ions reduces the MICof the tested biocides. In particular, the MIC reduction is expressed bya MIC ratio (MIC_(without Li)/MIC_(Li)) of ≥1.1.

TABLE 5 Analysis of the MIC reduction for various biocides Li⁺ conc./MIC active/ aequeous aequeous Biocide/Active Strain mM ppm mM ppm MICratio* Li⁺ source/remark 1,6-Dihydroxy-2,5-dioxane rOmyAK no Li⁺ noLi⁺ >13.1 >1593 — Li₂CO₃ (CAS NO. 3586-55-8) Li⁺ 197 Li⁺ 1380 8.71062 >1.5 Li⁺ 423 Li⁺ 2964 5.8 708 >2.25 Ampicilin E. coli no Li⁺ no Li⁺0.016 5.7 — Li₂CO₃ (CAS NO 69-53-4) Li+ 423 Li+ 2964 0.001 0.4 16Benzisothiazolinone (BIT) S. aureus no Li⁺ no Li⁺ >4.7 >708 — Li₂CO₃(CAS NO 2634-33-5) Li⁺ 423 Li⁺ 2964 2.3 354 >2 S. aureus no Li⁺ no Li⁺7.94 1200 — Li₂CO₃/Curative treatment Li+ 329 Li+ 2305 3.97 600 2Bronopol E. coli no Li⁺ no Li⁺ 0.53 106.2 — Li₂CO₃ (CAS NO 52-51-7) Li+197 Li+ 1380 0.18 35.4 3 E. coli no Li⁺ no Li⁺ >0.45 >90 — Li₂CO₃ Li+172 Li⁺ 1205 0.12 24 >3.75 S. aureus no Li⁺ no Li⁺ 0.90 180 — Li₂CO₃ Li⁺197 Li⁺ 1380 0.45 90 2 Li⁺ 329 Li⁺ 2305 0.15 30 6 Li⁺ 423 Li⁺ 2964 0.059 20 S. aureus no Li⁺ no Li⁺ 0.90 180 — Li₂CO₃ Li⁺ 172 Li⁺ 1205 0.15 306 4-Chloro-3-methylphenol E. coli no Li⁺ no Li⁺ 2.48 354 — Li₂CO₃ (CASNO 59-50-7) Li⁺ 197 Li⁺ 1380 1.24 177 2 Li⁺ 329 Li⁺ 2305 0.62 88.5 4 S.aureus no Li⁺ no Li⁺ 3.72 531 — Li₂CO₃ Li⁺ 423 Li⁺ 2964 2.48 354 1.5CMT/MIT (weight ratio 3:1) S. aureus no Li⁺ no Li⁺ 0.11 28.32 — Li₂CO₃(CAS NO 55965-84-9) Li⁺ 197 Li⁺ 1380 0.03 7.08 4 Li⁺ 329 Li⁺ 2305 <0.03<7.08 >4 S. aureus no Li⁺ no Li⁺ >0.23 >60 — Li₂CO₃/Curative treatmentLi⁺ 423 Li⁺ 2964 0.11 30 >2 3.5-Dimethyltetrahydro-1,3,5- E. coli no Li⁺no Li⁺ 1.09 177 — Li₂CO₃ thiadiazine-2- Li⁺ 329 Li⁺ 2305 0.87 141.6 1.25(CAS NO 533-74-4) S. aureus no Li⁺ no Li⁺ >1.09 >177.4 — Li₂CO₃ Li⁺ 423Li⁺ 2964 0.44 70.8 >2.5 Formaldehyde rOmyAK no Li⁺ no Li⁺ >35.4 >1062 —Li₂CO₃ (CAS NO 50-00-0) Li⁺ 197 Li⁺ 1380 11.8 354 >3 E. coli no Li⁺ noLi⁺ >1.18 >35.4 — Li₂CO₃ Li⁺ 197 Li⁺ 1380 0.59 17.7 >2 S. aureus no Li⁺no Li⁺ >1.18 >35.4 — Li₂CO₃ Li⁺ 197 Li⁺ 1380 0.118 3.54 >10Glutaraldehyde S. aureus no Li⁺ no Li⁺ >0.35 >35.4 — Li₂CO₃ (CAS NO.111-30-8) Li⁺ 197 Li⁺ 1380 0.04 3.54 >10 Guanidinedodecyl monochlorideE. coli no Li⁺ no Li⁺ >0.13 >35.4 — Li₂CO₃ (CAS NO 13590-97-1) Li+ 197Li+ 1380 0.05 14.16 >2.4 Hexachlorodimethyl sulfone E. coli no Li⁺ noLi⁺ 0.12 35.4 — Li₂CO₃ (CAS NO 3064-70-8) Li⁺ 197 Li⁺ 1380 0.07 21.241.67 S. aureus no Li⁺ no Li⁺ 0.09 28.32 — Li₂CO₃ Li⁺ 329 Li⁺ 2305 0.0721.24 1.33 Methylene bis(thiocyanate) S. aureus no Li⁺ no Li⁺ 2.18 283.2— Li₂CO₃ (CAS NO 6317-18-6) Li+ 329 Li+ 2305 0.54 70.8 4.042-Methyl-2H-isothiazolin-3-one rGDA-IT no Li⁺ no Li⁺ 1.54 177 — Li₂CO₃(MIT) Li⁺ 197 Li⁺ 1380 0.92 106.2 1.67 (CAS NO 2682-20-4) rOmyAK no Li⁺no Li⁺ 0.92 106.2 — Li₂CO₃ Li⁺ 197 Li⁺ 1380 0.92 106.2 1 Li⁺ 329 Li⁺2305 0.31 35.4 3 Li⁺ 423 Li⁺ 2964 0.15 17.7 6 E. coli no Li⁺ noLi⁺ >1.54 >177 — Li₂CO₃ Li⁺ 197 Li+ 1380 0.61 70.8 >2.5 S. aureus no Li⁺no Li⁺ >1.54 >177 — Li₂CO₃ Li⁺ 329 Li⁺ 2305 <0.31 <35.4 >5 Sodiumpyrithione E. coli no Li⁺ no Li⁺ 3.56 531 — Li₂CO₃ (CAS NO 3811-73-2)Li+ 197 Li+ 1380 1.19 177 3 S. aureus no Li⁺ no Li⁺ >4.75 >7.8 — Li₂CO₃Li⁺ 423 Li⁺ 2964 2.37 354 >2 S. aureus no Li⁺ no Li⁺ >6.04 >900 —Li3Citrate Li⁺ 19 Li⁺ 135 2.01 300 >3 Li⁺ 96 Li⁺ 670 1.01 150 >62-Phenylphenol (OPP) rOPP no Li⁺ no Li⁺ >9.36 >1539 — Li₂CO₃ (CAS NO90-43-7) Li⁺ 197 Li⁺ 1380 2.08 354 >4.5 Li⁺ 329 Li⁺ 2305 1.04 177 >9rOPP no Li⁺ no Li⁺ 0.53 90 — Li₂CO₃ Li⁺ 172 Li⁺ 1205 0.26 45 2 E. colino Li⁺ no Li⁺ 3.12 531 — Li₂CO₃ Li⁺ 197 Li⁺ 1380 2.08 354 1.5 S. aureusno Li⁺ no Li⁺ 1.76 300 — Li₂CO₃ Li⁺ 53 Li⁺ 370 0.88 150 2 S. aureus noLi⁺ no Li⁺ 1.76 300 — LiOH Li⁺ 67 Li⁺ 470 0.18 30 10 Biocide mixture(25% (w/w) rGDA-IT no Li⁺ no Li⁺ N/A >1593 — Li₂CO₃ glutaraldehyde (CASNO. 111-30- Li⁺ 197 Li⁺ 1380 N/A 1239 >1.29 8) and 1.5% (w/w) CMIT/MITLi⁺ 329 Li⁺ 2305 N/A <177 >9 (weight ratio CMIT/MIT 3:1) E. coli no Li⁺no Li⁺ N/A 177 — Li₂CO₃ (CAS NO. 55965-84-9) Li⁺ 197 Li⁺ 1380 N/A 70.82.5 Li⁺ 329 Li⁺ 2305 N/A 17.7 10 S. aureus no Li⁺ no Li⁺ N/A 354 —Li₂CO₃ Li⁺ 197 Li⁺ 1380 N/A 35.4 10 Polyethoxyethoxyethylguanidinium E.coli no Li⁺ no Li⁺ >0.71 >708 — Li₂CO₃ hexachlorid Li⁺ 197 Li⁺ 1380 0.53531 >1.33 (CAS NO 374572-91-5) Li⁺ 423 Li⁺ 2964 0.09 88.5 >8*MIC_(without Li)/MIC_(Li)

The invention claimed is:
 1. A process for reducing the minimuminhibitory concentration (MIC) of a biocide against at least one strainof bacteria and/or at least one strain of yeast and/or at least onestrain of mould in an aqueous preparation, the process comprising thesteps of: a) providing an aqueous preparation, b) providing at least onebiocide selected from the group consisting of phenols, halogenatedphenols, halogen-containing compounds, halogen-releasing compounds,isothiazolinones, guanidines, sulfones, thiocyanates, pyrithiones,antibiotics, β-lactam antibiotics, quaternary ammonium salts, peroxides,perchlorates, amides, amines, heavy metals, biocidal enzymes, biocidalpolypeptides, azoles, carbamates, glyphosates, sulphonamides, and anymixture thereof, c) providing at least one water soluble source oflithium ions, d) contacting the aqueous preparation of step a) with theat least one biocide of step b), wherein the at least one biocide iseffective against at least one strain of bacteria and/or at least onestrain of yeast and/or at least one strain of mould when present in theaqueous preparation, e) contacting the aqueous preparation of step a)before and/or during and/or after step d) with the at least one watersoluble source of lithium ions of step c), wherein the amount of thelithium ions and the amount of the at least one biocide are selected sothat the minimum inhibitory concentration (MIC) of the biocide meetsmeet equation (I):MIC_(withoutLi)/MIC_(Li)>1.1  (I) wherein MIC_(withoutLi) is the minimuminhibitory concentration (MIC) of the at least one biocide against theat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould without the at least one watersoluble source of lithium ions in ppm, calculated relative to the weightof water in the aqueous preparation of step a), MIC_(Li), is the minimuminhibitory concentration (MIC) of the at least one biocide against theat least one strain of bacteria and/or at least one strain of yeastand/or at least one strain of mould with the at least one water solublesource of lithium ions in ppm, calculated relative to the weight ofwater in the aqueous preparation of step a), wherein the total amount oflithium ions is selected from 15.0 to 800.0 mMol/L, calculated relativeto the weight of water in the aqueous preparation, and wherein theamount of the at least one biocide is selected from 0.4 to 6500.0 ppm,calculated relative to the weight of water in the aqueous preparation;and wherein the at least one biocide is free of aldehyde-releasingand/or aldehyde-based biocides.
 2. The process according to claim 1,wherein the aqueous preparation of step a) comprises: (i) at least oneinorganic particulate material, and/or (ii) at least one organicmaterial.
 3. The process according to claim 2, wherein the at least oneinorganic particulate material is selected from the group consisting ofnatural ground calcium carbonate, natural and/or synthetic precipitatedcalcium carbonate, dolomite, kaolin, talcum, aluminium hydroxide,aluminium silicate, titanium dioxide, and any mixture thereof, and theat least one organic material is selected from the group consisting ofcarbohydrates, starch, sugar, cellulose and cellulose based pulp,glycerol, hydrocarbons, and any mixture thereof.
 4. The processaccording to claim 2, wherein the at least one inorganic particulatematerial is natural ground calcium carbonate and/or syntheticprecipitated calcium carbonate.
 5. The process according to claim 1,wherein the aqueous preparation of step a) and/or of step d) and/or ofstep e) has: (i) a pH value of from 2 to 12, and/or (ii) a solidscontent of up to 85.0 wt.-%, based on the total weight of the aqueouspreparation.
 6. The process according to claim 1, wherein the aqueouspreparation of step a) and/or of step d) and/or of step e) has: (i) a pHvalue of from 6 to 12, and/or (ii) a solids content of from 10.0 to 82.0wt.-%, based on the total weight of the aqueous preparation.
 7. Theprocess according to claim 1, wherein the aqueous preparation of step a)and/or of step d) and/or of step e) has: (i) a pH value of from 7 to10.5, and/or (ii) a solids content of from 20.0 to 80.0 wt.-%, based onthe total weight of the aqueous preparation.
 8. The process according toclaim 1, wherein the at least one strain of bacteria is selected fromthe group consisting of gram-negative bacteria, gram-positive bacteria,and any mixture thereof.
 9. The process according to claim 1, wherein:(i) the at least one strain of bacteria is selected from the groupconsisting of Methylobacterium sp., Salmonella sp., Escherichia sp.,Escherichia coli, Shigella sp., Enterobacter sp., Pseudomonas sp.,Pseudomonas mendocina, Bdellovibrio sp., Agrobacterium sp., Alcaligenessp., Flavobacterium sp., Rhizobium sp., Sphingobacterium sp., Aeromonassp., Chromobacterium sp., Vibrio sp., Hyphomicrobium sp., Leptothrixsp., Micrococcus sp., Staphylococcus sp., Staphylococcus aureus,Agromyces sp., Acidovorax sp., and any mixture thereof, and/or (ii) theat least one strain of yeast is selected from the group consisting ofSaccharomycotina, Taphrinomycotina, Schizosaccharomycetes,Basidiomycota, Agaricomycotina, Tr emellomycetes , Pucciniomycotina,Microbotryomycetes, Candida sp., Candida albicans, Candida tropicalis,Candida stellatoidea, Candida glabrata, Candida krusei, Candidaguilliermondii, Candida viswanathii, Candida lusitaniae, Yarrowia sp.,Yarrowia lipolytica, Cryptococcus sp., Cryptococcus gattii, Cryptococcusneofarmans, Zygosaccharomyces sp., Rhodotorula sp., Rhodotorulamucilaginosa, and any mixture thereof, and/or (iii) the at least onestrain of mould is selected from the group consisting of Acremonium sp.,Alternaria sp., Aspergillus sp., Cladosporium sp., Fusarium sp., Mucorsp., Penicillium sp., Rhizopus sp., Stachybotrys sp., Trichoderma sp.,Dematiaceae sp., Phoma sp., Eurotium sp., Scopulariopsis sp.,Aureobasidium sp., Monilia sp., Botrytis sp., Stemphylium sp.,Chaetomium sp., Mycelia sp., Neurospora sp., Ulocladium sp.,Paecilomyces sp., Wallemia sp., Curvularia sp., and any mixture thereof.10. The process according to claim 1, wherein the at least one watersoluble source of lithium ions is at least one lithium salt.
 11. Theprocess according to claim 1, wherein the at least one water solublesource of lithium ions is at least one lithium salt selected from thegroup consisting of lithium carbonate, lithium chloride, lithiumhydroxide, lithium phosphate, lithium citrate, lithium maleate, lithiumacetate and lithium lactate, polymeric salts of lithium, and any mixturethereof.
 12. The process according to claim 1, wherein the at least onewater soluble source of lithium ions is a polymeric salt of lithiumselected from the group consisting of lithium salts of acrylichomopolymers, acrylic copolymers, copolymers of acrylic acid and maleicacid and/or acrylamide, polyphosphates, and any mixture thereof.
 13. Theprocess according to claim 1, wherein the at least one water solublesource of lithium ions is a polymeric salt of lithium selected from thegroup consisting of Li₂Na₂polyphosphate, lithium-sodiumhexamethaphosphate, lithium polyacrylate.
 14. The process according toclaim 1, wherein the at least one biocide is selected to be: (i) in anamount of at least 9%, below the minimum inhibitory concentration (MIC)of the at least one biocide for the at least one strain of bacteriaand/or at least one strain of yeast and/or at least one strain of mould,and/or (ii) in an amount of from 0.5 ppm to 6000 ppm, calculatedrelative to the weight of water in the aqueous preparation.
 15. Theprocess according to claim 1, wherein the at least one biocide isselected to be in an amount of at least 33%, below the minimuminhibitory concentration (MIC) of the at least one biocide for the atleast one strain of bacteria and/or at least one strain.
 16. The processaccording to claim 1, wherein the at least one biocide is selected to bein an amount of at least 50%, below the minimum inhibitory concentration(MIC) of the at least one biocide for the at least one strain ofbacteria and/or at least one strain.
 17. The process according to claim1, wherein the at least one biocide is selected to be in an amount of atleast 75%, below the minimum inhibitory concentration (MIC) of the atleast one biocide for the at least one strain of bacteria and/or atleast one strain.
 18. The process according to claim 1, wherein theamount of the lithium ions and the amount of the at least one biocideare selected so that the minimum inhibitory concentration (MIC) of thebiocide meets equation (Ia), or equation (Ib), or equation (Ic):MIC_(withoutLi)/MIC_(Li)>1.5  (Ia)MIC_(withoutLi)/MIC_(Li)>2.0  (Ib)MIC_(withoutLi)/MIC_(Li)>4.0  (Ic) wherein MIC_(withoutLi)is the minimuminhibitory concentration (MIC) of the biocide against the at least onestrain of bacteria and/or at least one strain of yeast and/or at leastone strain of mould without the at least one water soluble source oflithium ions in ppm calculated relative to the weight of water in theaqueous preparation of step a), MIC_(Li) is the minimum inhibitoryconcentration (MIC) of the biocide against the at least one strain ofbacteria and/or at least one strain of yeast and/or at least one strainof mould with the at least one water soluble source of lithium ions inppm calculated relative to the weight of water in the aqueouspreparation of step a).
 19. The process according to claim 1, whereinthe total amount of lithium ions is selected from 15.0 to 700.0 mMol/L,calculated relative to the weight of water in the preparation.
 20. Theprocess according to claim 1, wherein step e) is carried out before stepd).
 21. The process according to claim 1, wherein step d) and/or step e)is/are repeated one or more times.